Astronomy 02.2021

MARS 2020 ARRIVES AT THE RED PLANET p.24

FEBRUARY 2021

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FEBRUARY 2021

VOL. 49, NO. 2

CONTENTS 24 ON THE COVER

Comet C/2020 F3 NEOWISE
stormed into our skies in July and
put on a spectacular — though
relatively brief — show. JOSE CHAMBO

FEATURES 34 48 COLUMNS

16 COVER STORY Star Dome and Studying galaxies Strange Universe 14
Paths of the Planets with amateur images
Top 10 space BOB BERMAN
stories of 2020 RICHARD TALCOTT; Advances in our
ILLUSTRATIONS BY ROEN KELLY understanding of galaxy Secret Sky 58
An international fleet of formation aren’t just
spacecraft set off for Mars, 40 STEPHEN JAMES O’MEARA
Crew Dragon carried coming from large,
astronauts to the ISS, and Corona light professional telescopes. Binocular Universe 59
a global pandemic left
its mark on astronomy. Missed last DAVID MARTÍNEZ-DELGADO PHIL HARRINGTON
year’s annular AND R. JAY GABANY
ALISON KLESMAN AND eclipse? Observing Basics 60
JAKE PARKS We’ve got you 54
covered with GLENN CHAPLE
24 some of the best We review Celestron’s
shots out there. 60th anniversary C8 7
New Mars rover
begins its mission JAY PASACHOFF The NexStar Evolution 8HD QUANTUM GRAVITY
With StarSense, a limited
Perseverance is more than just 46 edition telescope, combines Everything you need to
Curiosity’s double — it will all of Celestron’s fanciest know about the universe
hunt for ancient life, cache Spend some trappings to produce a superb, this month: OSIRIS-
samples, and pave the way for time in Auriga top-of-the-line instrument. REx overflows, a look at
human explorers. JIM BELL the birthplace of stars,
With three Messier objects DAVID J. EICHER a twisted solar system,
32 and loads of other bright and more.
targets, the Charioteer has a 62
Sky This Month lot to offer. MICHAEL E. BAKICH IN EVERY ISSUE
Ask Astro
Twilight planets delight. From the Editor 5
Galactic traffic jam. Astro Letters 6
MARTIN RATCLIFFE AND New Products 61
ALISTER LING Advertiser Index 61
Reader Gallery 64
ONLINE My Science Trips and Sky This Ask Astro Breakthrough 66
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4 ASTRONOMY • FEBRUARY 2021

FROM THE EDITOR

A renewal for Editor David J. Eicher
stargazing Design Director LuAnn Williams Belter

The Orion and As I write this in late 2020, the world EDITORIAL
Horsehead nebulae has been upended by a pandemic for Senior Editor Mark Zastrow
in the winter Milky over eight months now. More sig- Production Editor Elisa R. Neckar
Way are among nificant than any health crisis in a century, the Senior Associate Editor Alison Klesman
numerous treasures coronavirus outbreak has changed all our Associate Editor Jake Parks
rediscovered by lives, in some ways perhaps permanently. Associate Editor Caitlyn Buongiorno
housebound Despite all the negative aspects of the pan- Editorial Assistant Hailey McLaughlin
skywatchers. demic — social distancing away from friends
and family, economic fallout, and, most ART
TONY HALLAS importantly, the terrible toll of death and sick- Contributing Design Directors Kelly Katlaps, Elizabeth M. Weber
ness — there has been one apparent benefit Illustrator Roen Kelly
from these circumstances. We’ve seen quite a Production Specialist Jodi Jeranek
surge of astronomy hobbyists and their neigh-
bors, friends, and acquaintances discovering CONTRIBUTING EDITORS
or rediscovering the sky. Michael E. Bakich, Bob Berman, Adam Block,
This year has been a good one for observational astronomy, no Glenn F. Chaple Jr., Martin George, Tony Hallas,
doubt. We had a beautiful naked-eye comet, C/2020 F3 NEOWISE. Phil Harrington, Korey Haynes, Jeff Hester, Alister Ling,
On the days before and following perihelion, July 3, it shone brighter Stephen James O’Meara, Martin Ratcliffe, Raymond Shubinski,
than first magnitude and displayed magnificent ion and dust tails. For Richard Talcott
Northern Hemisphere observers, the comet was visible all night in
mid-July, bright enough to get non-astronomers to take notice. EDITORIAL ADVISORY BOARD
We’ve also had wonderful planetary oppositions this year. Jupiter Buzz Aldrin, Marcia Bartusiak, Jim Bell, Timothy Ferris,
and Saturn reached their brightest, opposite the Sun in the sky, in Alex Filippenko, Adam Frank, John S. Gallagher lll,
the second and third weeks of July. Perched in the southeast beside Daniel W. E. Green, William K. Hartmann, Paul Hodge,
Sagittarius, the two planets gleamed brilliantly. And novice skygazers Edward Kolb, Stephen P. Maran, Brian May, S. Alan Stern,
were impressed that a pair of binoculars with 10x magnification could James Trefil
reveal the Galilean moons of Jupiter astride the big planet’s disk. The
array of planets continued when Mars reached opposition in mid- Kalmbach Media
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ASTRO LETTERS

We welcome Teaching the teacher just making it up. Could that have been a “sighting” of
your comments I taught high school biology for 42 years. I always men- Haidinger’s Brush? — Tim Geddert, Fresno, CA
at Astronomy Letters, tioned the sense of smell could evoke a strong memory
P.O. Box 1612, or emotional response, but I never knew why this was Thoughts on “Learning the hard way”
Waukesha, WI 53187; true. Then comes along Associate Editor Jake Parks, My compliments to Jeff Hester
or email to letters@ who beautifully taught the teacher with his explana- on his article, “Learning the hard
astronomy.com. tion of how smell works in the sidebar for “What does way,” in the September issue. It was
Please include your Titan smell like?” in the September issue. To my more a very succinct explanation about
name, city, state, and than 5,000 former students: I apologize for not explain- the workings of the virus, and it
country. Letters may ing “the why” of the issue as well as Jake Parks can. placed the blame without using
be edited for space names. As a retired registered nurse, I especially appre-
and clarity. — Jim McLeod, Charlotte, NC ciated it, but was surprised to see a health article in an
astronomy magazine, even though it affects everyone.
A composite image of Seeing colors Thanks for that very relevant article. — Alice Mack,
Titan, from the Cassini Thank you, Stephen O’Meara, for introduc-
mission. NASA ing me to Haidinger’s Brush in the October Fort Myers, FL
issue. I had never heard of it but will
certainly watch for it. Decades ago, I had Correction
a shirt, and I believe it had wide hori- In the article “What does Titan smell like” in the
zontal stripes of blue and white. When September 2020 issue, the caption on page 31 incor-
I picked up that shirt, I would often see rectly stated the diameter of Titan is about 1,600 miles
yellow bands running vertically across (2,600 kilometers). Rather, Titan’s radius is about
the pattern. I’d mention it to others, and 1,600 miles (2,600 km).
I think they considered me either crazy or

ADVERTISEMENT

If Discoverer Ramesh Varma (India) had been academic qualified PhD scientist (not citizen scientist); discovery claim instead of being an advertisement, would have appeared
in all Science Journals as publication resulting to make it viral among the concerned. (Mode of new discovery information set by the Academic World is a curse on the mankind).

A new discovery claim magnetic bar to North Pole to repeat the cycle (why is it not Ÿ Smell/Odour particles are the chemical particles
vise- versa?). Further; if South Pole of the magnetic compass released by the decomposition of the organic/ inorganic
over invisible state of the matter: is pointed towards the North Pole of the Bar-magnet it forms chemical matter so smell particles are also a state of the
The entire Universe is materialistic; no pocket of the the same pattern of magnetic rays as North Pole of the matter.
Universe is with absolute nothing. What we see, we compass forms with the South Pole of the bar -magnet. Then
understand it a matter but whatsoever (particles and rays etc) why does the forward direction of the rays differs over North Ÿ Gravity is not a wave or particle matter but it is directly
in the space we can’t see that too is matter (materialistic). and South Pole of the bar-magnet?. Pattern formed by the related to the matter of any kind including white-matter.
Fact: Whatsoever trillions and trillions of stars release in the magnetic rays must be the mirror reflection image pattern as Scientists have claimed that they have detected
form of invisible matter (rays, particles, gases etc) by losing shown below under the sketch ‘B’.
their mass in their respective galaxies or in the space that all is gravitational waves emerging from clubbing (collision) of two
mixture of different kinds of the matter to be called as white Sketch-B nearby black holes. In fact it was not the gravitational waves
matter which has been falsely understood by the Scientists but were compressions and rarefactions created in the space
as dark matter. Further, presence of invisible matter in the Pattern of rays as understood by the Discovery Claimer occupied by the white matter as medium, like by the sound in
galaxies called as dark matter by the Scientists was noticed in air medium.
the year 1930s whereas Scientists came to know of the solar Above stated fact and sketch ‘B’ and ‘C’ below confirms Ÿ Energy is not merely energy but it is a state of the
wind in the 1940s. With the result it has been understood that that magnetic particles rays ‘N’ and ‘S’ has been produced
Sun loses mass to generate whatsoever it ejects to solar from the space matter NS by the magnetic matter (Bar matter (white matter), which acts as energy under
space. It is an utmost surprise that until now no one has linked magnet) acting as catalyst and rays ‘N’ and ‘S’ having the specific conditions.
mass lost by the stars to generate invisible white matter property to re-unite again to form stable white matter NS. There is no dark energy, which is pulling the galaxies
(falsely understood as dark matter. and other celestial objects towards outer space (or expanding
Ÿ Rays of all kinds are materialistic: A ray is composed The following sketch ‘C’ as understood by the Discovery the Universe) but it is the outwards going white matter
Claimer also justifies repulsion and attraction to bar magnets particles and rays generated and released by the stars,
of finest form of spherical particles. All spherical particles by the magnetic rays ‘S’ and ‘N’ forming a mirror reflection planets and other objects that are pushing the celestial
by closely touching each other form a row or a ray. image pattern. objects along with the galaxies towards the outer presumed
Density, diameter and chemical properties of the end of the Universe.
spherical particles make a ray of different kind. Ÿ Electrons of an atom, lightning or of the electricity Conclusion: Periodic table is for the visible states of the
Ÿ Magnetic rays: are composed of finest form of the are a state of the matter, which act as energy under matter (solid, liquid and gases) but so far the World has not
particle matter. Iron or any other magnetic material acting specific conditions. Generator generates electrons from been able to correctly understand physical, chemical and
as catalyst splits a kind of stable form of white matter of a kind of the space’s white matter along with the biochemical properties of the invisible matter. Correct
the space say ‘NS’ to two unstable forms of white matter magnetic particle matter. In case terminals understanding of true states of the matter and particularly
particles rays say ‘N’ and ‘S’; both rays intend to re-unite (positive/negative) of the generator are not connected to the invisible matter by the Discovery Claimer has resulted to
to form again stable white matter ‘NS’. any device or to the earth; produced electrons disappear conclude that Prime and only one Fundamental of the
Forward direction of the magnetic particles rays: to space in the form of white matter. Universe for its existence, formation and working is the
Information taken from the academic books and Internet ‘Universe is materialistic’. Already understood four
shows pattern of the magnetic rays as shown over the sketch ‘A’. fundamentals of the Universe by the World are the sub-
fundamentals of it. As under the Religion belief there would be
What does the Discovery claimer has understood? only one God (not so many). Similarly. there can’t be four
Understood pattern suggests that magnetism or Fundamentals. The said discovered and claimed Prime and
only one Fundamental would lead to replace all theories,
magnetic rays are being generated at the North Pole and on postulations, hypothesises and speculations with the facts.
entering as South Pole; magnetic rays travel through the Ÿ Must read discovery claim advertisements over Astronomy
and Light published in the magazine ‘ASTRONOMY’. which
appeared in the issue Feb 2020 to August 2020 (7 Nos) and
over subject ‘Light’ (Physics) January 2021.
Ÿ Much more over the discovery claim is over the website
www.newtonugeam.com under title MATERIALISTIC
UNIVERSE.
Ÿ After going through the discovery claim as stated above;
please reply that why above stated discovered and claimed
facts are not correct.
E-mail: ramesh_varma @newtonugeam.com

6 ASTRONOMY • FEBRUARY 2021

QG QUANTUM GRAVITYEVERYTHING YOU NEED TO KNOW ABOUT THE UNIVERSE THIS MONTH

SNAPSHOT

TREASURES OF THE COSMOS

X-RAY: NASA/CXC; OPTICAL: NASA/STSCI. BOTTOM FROM LEFT: ESO/M. KORNMESSER; NOBEL MEDIA. ILL. NIKLAS ELMEHED; NASA’S GODDARD SPACE FLIGHT CENTER/SDO/JOY NG If humans could see beyond remnant of a powerful supernova that a powerful collision. And the Helix
just visible light, the universe exploded 160,000 years ago. On the Nebula (bottom right) is a planetary
might look like these images, other hand, Eta Carinae (bottom left) nebula, providing a glimpse at what
which combine observations is a binary star system still waiting to our own Sun might look like 5 billion
from NASA’s Chandra X-Ray go supernova. The Cartwheel Galaxy years in the future, after it expels
Observatory with data from (bottom center) was created after one its outer layers and becomes a white
telescopes that pick up different galaxy punched through another in dwarf. — HAILEY ROSE MCLAUGHLIN
parts of the electromagnetic
spectrum. This multiwave- HOT SPAGHETTIFIED STAR NOBEL PRIZE LUNAR PHOTOBOMB
length approach to observing BYTES
helps researchers gain a fuller Astronomers using Three scientists whose On October 16, 2020,
understanding of how these ESO’s Very Large research focuses on NASA’s Solar Dynamics
cosmic wonders behave in Telescope and New black holes shared the Observatory spacecraft
the depths of space. M82 (top Technology Telescope 2020 Nobel Prize in tracked a stunning lunar
left) is a galaxy facing Earth got an unprecedented Physics. Half the award transit. At the transit’s
edge-on, giving us a unique look at a black hole went to Roger Penrose, peak, the Moon covered
look at outflows of gas driven devouring a star, finding while the other half about 44 percent of the
by star formation and super- that such events send was jointly awarded to Sun’s disk.
novae. Abell 2744 (top center) out powerful blasts Reinhard Genzel and
is a galaxy cluster millions of material that can Andrea Ghez.
of light-years across, while obstruct our view.
SN 1987A (top right) is the

WWW.ASTRONOMY.COM 7

QUANTUM GRAVITY

OSIRIS-REX OVERFLOWS
WITH SAMPLES

NASA’s daring asteroid mission collected so many
rocks that the craft couldn’t contain them all.

TOUCH AND GO.

OSIRIS-REx’s sample-
collection mechanism
makes contact with
the surface of Bennu
(left) and kicks up a
cloud of rocks and
dust (right). NASA/

GODDARD/UNIVERSITY OF ARIZONA

OSIRIS-REx is getting ready to Bennu is a dark rubble pile of an The spacecraft’s cylindrical sample-
come home — but like a lot of asteroid more than 200 million miles collection head, mounted to a robotic
travelers, it has collected more souve- (322 million kilometers) from Earth. arm, pressed into the regolith — the
nirs than will fit in its luggage. Launched in 2016, OSIRIS-REx arrived in surface layer of dust and rocks — for
This highly relatable problem is a late 2018 and began an intensive survey of six seconds. At the same time, it fired
good one to have, though. It means the 1,640-foot-wide (500 meters) world. a canister of nitrogen gas, kicking up a
the spacecraft’s Touch-And-Go (TAG) cloud of material into a collecting area
attempt to collect rocks and dust Right away, Bennu threw the mission inside the rim of the sample head.
from the surface of asteroid Bennu for a loop. The team expected a smooth
October 20 was a smashing success. surface, like gravel or beach sand. “I must have watched [the video of
OSIRIS-REx — short for Origins, Instead, the landscape was strewn with the TAG attempt] about 100 times last
Spectral Interpretation, Resource boulders, forcing a complete overhaul night before I finally got a little bit of
Identification, and Security-Regolith of the craft’s landing software and a shuteye,” said Dante Lauretta of the
Explorer — is now the third mission to painstaking analysis of the asteroid’s University of Arizona, the mission’s
nick rocks from an asteroid and NASA’s surface to identify a safe landing site. principal investigator, at a media
first, following Japan’s two Hayabusa briefing on October 21. “I dreamed
missions. Nearly two years of work came to frui- of a wonderworld of Bennu regolith
tion on October 20. First, OSIRIS-REx particles floating all around me.”
navigated down to the surface of Bennu.

8 ASTRONOMY • FEBRUARY 2021

TWISTED SOLAR SYSTEM ESO/L. CALÇADA, EXETER/KRAUS ET AL. QUICK
TAKES
The planets in our solar system
orbit the Sun on nearly the same READING TEA LEAVES
plane. But not every system is as
harmonious. GW Orionis con- Cosmonauts aboard the
tains three young stars sowing International Space Station tracked
chaos. Astronomers have known
for more than a decade that this down a pesky minor air leak by
system (right) is surrounded by tearing open a tea bag inside the
a disk of gas and dust, and new affected module and watching the
observations show that the stars’ gravitational meddling has formed three leaves drift toward the puncture.
distinct rings within the disk. The effects have driven the innermost ring
onto a entirely different plane as the others, shown in this artist’s concept PHOSPHINE ON VENUS?
(left). The disks aren’t the only crooked objects — the orbits of the stars
themselves are also misaligned in this skewed system. —CAITLYN BUONGIORNO Astronomers say they have
detected phosphine in the clouds
CONTINGENCY PLANS On one hand, that probably means of Venus. The molecule, which is
OSIRIS-REx collected even more associated with biotic processes
Two days after the TAG attempt, material than is visible — perhaps
mission engineers moved the collection up to 4.4 pounds (2 kilograms), the on Earth, may be produced by
head in front of the craft’s cameras to researchers estimate. “It’s very exciting, some unknown chemical process
evaluate their haul. Rocks were plainly very surprising, but overall excellent or even microbial life. (See “Top 10
visible inside the apparatus — at least news,” Lauretta told reporters on space stories of 2020” on page 16
14 ounces (400 grams), they estimated. October 23.
for more information.)
But the team also saw something con- Still, the leaking samples injected a
cerning: The mylar flap meant to seal in sense of urgency into the mission. The ALTERED REALITY
those precious rock samples was stuck team cancelled further evaluations
open. A handful of Bennu particles just of their haul to avoid jostling more Paradox-free time travel is
a few centimeters wide were wedged particles out of the open flap, instead mathematically possible, University
between the flap and the sample head’s opting to stow it as soon as possible
inner rim. Furthermore, time-lapse to minimize losses. By October 28, of Queensland researchers find.
imagery showed some of the invaluable the material had been secured inside According to their calculations, if
pebbles escaping into space. It appeared the craft’s sealed capsule, ready for its
the collection head was stuffed full and journey back to Earth. you traveled back in time and
literally overflowing. interacted with your past self,
The team estimates that the sample events would adjust themselves
RUNNETH OVER. OSIRIS-REx’s sample head likely bled up to a few ounces of
material while it was exposed to space. around you to ensure a
collection head is seen here with Bennu But the remainder still greatly exceeds consistent timeline.
particles wafting out. The head’s mylar flap the mission’s target of 2.1 ounces (60 g)
(the faint white crescent on the left side of and is on track to become the largest DEARTH METAL
the inner rim) is visibly wedged open. NASA set of asteroid samples ever returned to
Earth by a spacecraft. Astronomers have found that stars
in the globular cluster RBC EXT8 in
Scientists hope scrutinizing the
samples will yield insight into the the Andromeda Galaxy have, on
formation of the solar system, as well average, 800 times less iron than
as life on Earth. They expect to have
Bennu’s rocks in their labs shortly after our Sun, making it the most
the craft delivers on September 24, 2023. metal-poor globular cluster known.

— MARK ZASTROW MAIDEN FLIGHT

China launched an experimental
reusable spacecraft September 4
from the Jiuquan Satellite Launch
Center. The craft, which deorbited
and landed after a two-day mission
shrouded in secrecy, is rumored to
be a robotic spaceplane akin to the

U.S. Air Force X-37B.

MAKING WAVES

In late October, the LIGO and Virgo
observatories announced the

discovery of 39 gravitational-wave
signals caused by binary black

hole or neutron star collisions. The
signals, received between

April and October 2019, add to
11 previous detections. — M.Z.

WWW.ASTRONOMY.COM 9

QUANTUM GRAVITY

Tangled in a cosmic web But how did these galaxies and the
supermassive black hole find enough
Astronomers have long struggled to ESO/L. CALÇADA material to grow so soon after the Big
understand how supermassive black Bang? The key is likely the vast cosmic
holes could have formed in the early SPIDER’S WEB. This artist’s concept shows six web. This universal scaffolding is woven
universe. Such cosmic goliaths must have through the entire cosmos, connecting
formed quickly — less than a billion years recently discovered galaxies surrounding a distant galaxies, galaxy clusters, and
after the Big Bang — defying our cur- supermassive black hole in the early universe. It galaxy superclusters through threads of
rent understanding of how fast a black is the first such tight-knit group of galaxies seen faint gas known as filaments, which likely
hole can feed and grow. Additionally, so soon after the Big Bang. formed around clumps of dark matter.
it remains unclear exactly where these
giants found huge amounts of matter to within the cosmos’ first billion years. And The authors of the new study
gorge on. at the center of this galactic mosh pit lies think the supermassive black hole
a supermassive black hole a billion times and its surrounding galaxies, dubbed
New findings from the European the mass of the Sun. SDSS J1030+0524, likely fed on gas
Southern Observatory’s Very Large that was stockpiled in a tangled knot
Telescope, published October 1 in of cosmic web filaments.
Astronomy & Astrophysics, may provide
the answer. “The cosmic web filaments are like
spider’s web threads,” said lead author
The paper outlines six newly discov- Marco Mignoli in a press release. “The
ered galaxies spotted just 900 million galaxies stand and grow where the
years after the Big Bang, when the filaments cross, and streams of gas —
universe was only around 6 percent its available to fuel both the galaxies and
current age. This is the first time such a the central supermassive black hole —
close grouping of galaxies has been found can flow along the filaments.” — C.B.

PLANETARY SURFACE PRESSURES

UNDER PRESSURE. Surface pressure MERCURY VENUS EARTH MARS
is the pressure exerted on you by
the weight of the atmosphere above 0 92 1 0.01
your location. The composition and
thickness of a planet’s atmosphere ASTRONOMY: ROEN KELLY
affects the pressure at its surface — a
thicker, heavier atmosphere translates
to a higher surface pressure. On
Earth, the surface pressure at sea level
is 1 atmosphere, which is equivalent
to 14.696 pounds per square inch
(1.033 kg/cm2). This is how the other
terrestrial planets compare to our
own, as a ratio of Earth’s surface
pressure. — ALISON KLESMAN

FAST FACT

This measurement is not possible for
the outer planets, whose volumes are mostly

gas and lack traditional surfaces. They do
have solid cores, but these are so deep that

their location is not exactly known.

10 ASTRONOMY • FEBRUARY 2021

Source of fast radio bursts revealed SOPHIA DAGNELLO, NRAO/AUI/NSF

PENT-UP ENERGY. A AFTER MORE THAN A DECADE of detective think, could trigger powerful shock
work, astronomers have found the waves with the stunning magnetic
magnetar emits a burst best evidence yet for the cause of fast properties needed to produce FRBs.
of radiation from one side radio bursts, or FRBs. The culprit?
of its magnetic field in Magnetars, according to three papers However, we know of only a handful
this artist’s concept. published in Nature November 4. of magnetars in our Milky Way galaxy,
and they all seem too tame to cause
1/3000 FRBs have become one of the most these extreme signals. To know for
exciting enigmas in astronomy. For sure whether these stars could generate
The carbon astronomers, the mystery began with FRBs, astronomers would have to catch
footprint a burst of radio waves that traveled a Milky Way magnetar in the act.
of the 2020 1.6 billion light-years and arrived
meeting of at Earth on July 24, 2001. Lasting In late April 2020, a magnetar
the European just five milliseconds, it carried as dubbed SGR 1935+2154 began blasting
Astronomical much energy in radio waves as the out X-rays near the center of our gal-
Society — Sun puts out in an entire month. axy, some 30,000 light-years away. As
held virtually Incredibly, it went unnoticed until interest in this object built, astrono-
due to the 2006, when it was discovered in mers turned ground- and space-based
coronavirus archived data. Since then, radio obser- telescopes in its direction. They were
pandemic — vatories have spied dozens of FRB just in time to watch the activity build
as a fraction sources, but the nature of the objects to a crescendo: first X-ray bursts, then
of the carbon producing them has proven elusive. gamma rays — and eventually, the
footprint of blast of a fast radio burst. It was the
the previous Modeling has indicated that first FRB ever observed in our home
magnetars could act as “engines” for galaxy, as well as the first FRB clearly
year’s FRBs. Magnetars, short for “magnetic associated with a single object.
in-person stars,” are highly magnetic remnants
meeting in of massive dead stars. As a magnetar “This discovery paints a picture
Lyon, France. flares, it sends out blasts of energetic that some — and perhaps most — of
particles. Its powerful magnetic field these fast radio bursts from other gal-
then accelerates these particles around axies also originate from magnetars,”
the star, where models suggest the Christopher Bochenek, a graduate
particles ram into material from previ- student at Caltech and co-author
ous flares. Such collisions, researchers of one of the studies, said in a press
conference. —ERIC BETZ

WWW.ASTRONOMY.COM 11

QUANTUM GRAVITY

Simulations zoom in BIRTHPLACE
on dark matter
OF THE
Dark matter is a mys- from China, the U.S., and REPEATING HALOS. J. WANG, S. BOSE/CFA
terious material that Germany — began by INTERNATIONAL GEMINI OBSERVATORY/NOIRLAB/NSF/AURA ACKNOWLEDGMENT: PI: PATRICK HARTIGAN (RICE UNIVERSITY); IMAGE PROCESSING:STARS
makes up more than simulating a universe Inside a simulated PATRICK HARTIGAN (RICE UNIVERSITY), TRAVIS RECTOR (UNIVERSITY OF ALASKA ANCHORAGE), MAHDI ZAMANI & DAVIDE DE MARTIN
80 percent of all mat- filled with dark matter. region of the universe Stars are born within enor-
ter in the universe. This The result was similar 2 billion light-years mous clouds of gas and dust.
strange stuff permeates to those from previous across, large blobs While the Orion Nebula
and surrounds every computer simulations: a of dark matter are is one of the most famous
galaxy, and clumps of cosmic web of filaments the size of galaxy — and closest — examples,
dark matter, called halos, and clumps called dark clusters. By zooming the Carina Nebula is some
are where galaxies tend matter halos. in — the first inset is 500 times larger, making it
to form. Now, supercom- 700,000 light-years another favorite for research-
puter simulations have But the team then across, while the ers. This new image from the
found that these cosmic took their simulations a second inset is just Gemini Observatory captures
clumps of dark matter step further and focused 600 light-years the western wall of the Carina
look surprisingly alike, in on a small area, run- across — researchers Nebula like never before, tak-
no matter their size — ning the entire model resolved clumps of ing advantage of a technique
whether they encompass again for just that region. dark matter roughly known as adaptive optics,
monstrous galaxy clus- The team repeated the the size of Earth. which allows astronomers to
ters or are mini-blobs the process eight times, compensate for the effects of
size of Earth. effectively zooming in their surprise, the Earth’s turbulent atmosphere.
each time to reveal finer filament-and-clump In this image, researchers
The results of the and finer details. structure repeated have already spotted a num-
simulations, published itself down to the ber of unexpected structures,
September 2 in Nature, Prior to these simu- smallest scales including a long series of
show some of the most lations, astronomers they simulated, parallel ridges possibly
detailed models con- expected the smallest where the dark produced by a magnetic field,
structed to date of the clumps of dark matter to matter clumps are evidence of a strong wind
structure of dark matter. look different from the only the size of Earth. blowing off fragments from
largest halos, which may The similarity isn’t the cloud, and a possible jet
The authors — a be the building blocks of just visual: Analysis being ejected from a newly
team of researchers some galaxy clusters. To showed that the varia- formed star. — C.B.
tion in density — from
their center to their
fringes — in small and
large halos also mirrors
each other.
That information
could aid the search for
dark matter. While dark
matter does not interact
with normal matter, it
should give off a burst
of gamma-ray light
when it collides with its
antimatter equivalent
and the particles anni-
hilate each other. This
is most likely to happen
at the centers of dark
matter halos, where
the density is high. The
simulations’ results can
now help astronomers
understand how much of
this radiation they might
be able to detect. — M.Z.

12 ASTRONOMY • FEBRUARY 2021

PLANET CAPTURED
IN THE LIGHT OF A
DYING STAR
NASA/JPL-CALTECH/SWRI
NASA/JPL-CALTECH/GODDARD SPACE FLIGHT CENTERRESEARCHERS HAVE FOUND a Jupiter-sized planet orbitingits outer layers and loses most of its mass, leaving
the remains of an exhausted star some 80 light-years behind a smoldering stellar core. Distant objects
away. The international team of astronomers spotted within a system, such as asteroids and comets, can
the unlikely pair using NASA’s Transiting Exoplanet be pulled inward by this disruptive death. But these
Survey Satellite (TESS) and data from the retired objects are usually ripped apart by the star’s grav-
Spitzer Space Telescope. ity. This is the first timDdewWaaArsRfstFriEtosDnh. oAosmJtuspetiatrres,rW-hsDizae1vd8e5p6fla+on5ue3tn4,d
a planet that managedintothsisuarrtvisitv’secwonictehpt.itTshehpolasntest tar,
The dead star, dubbed WD 1856+534, is a white dwarf sweeping in toward themthaesyrtaahwravadeyuothrriaginninigatsteicdtusr5r0feintnitmoaerlbssiftat, ar-ge
— the stellar ember of a Sun-like star — only 40 percent of life. The finding alsobeefoxrepbaenindgsswthepet pcloossesriabsilthiteies of
the diameter of Earth. That makes it seven times smaller where life could managbsteeacrtotomhritenawgkaoefwf hihtsioteoldudtweeralrlsaf.eyewrsh, ere in
than the Jupiter-sized planet orbiting it, shown here the universe. — C.B.
in an artist’s concept. The planet, WD 1856 b, speeds
around its host every 34 hours. For comparison, it takes
Mercury 88 days to complete a single orbit.

When a star similar to our Sun runs out of fuel, it
balloons outward, forming a red giant that gobbles
up any planets in its path. Eventually, the star ejects

Sprites and elves frolic in Jupiter’s skies

K8P0V4L Lightning is familiar throughout the away from a cloud, leaving it negatively

solar system. But it isn’t the only electri- charged. This triggers sprites above the

cal outburst that can occur. Stunning, storm. Elves look more like expanding

evanescent events called sprites and doughnuts or rings and form when

elves are sometimes seen prancing electromagnetic pulses released during a

above thunderclouds on Earth. And thunderstorm slam into the ionosphere.

NASA’s Juno spacecraft appears to have Over the past four years, Juno’s

also captured these flashes on Jupiter Ultraviolet Spectrograph instrument

— the first time these events have captured 11 brief, bright flashes of

been observed on another planet. ultraviolet (UV) light lasting between

Both sprites (which stands 0.1 and 2.5 milliseconds. They are the

for Stratospheric/mesospheric first-ever lightninglike flashes recorded

Perturbations Resulting from Intense on Jupiter at UV wavelengths, and also

Thunderstorm Electrification) and the first TLEs spotted on another world.

elves (Emission of Light and Very The flashes originated exactly where

Low Frequency perturbations due to sprites and elves are assumed to form on

Electromagnetic Pulse Sources) are a Jupiter, above the water cloud layer where

type of transient luminous event, or lightning is generated. Scientists aren’t

TLE, lasting only milliseconds. sure which TLEs Juno saw — sprites or

Sprites typically have round, blobby elves — but now that they know what to

centers that sprout tendrils of light look for, the researchers think it will be

upward or downward. They occur when easier to spot these phenomena on Jupiter

lightning bolts funnel positive charge and in the clouds of other planets, too. —A.K.

CHANGING COLORS. On Earth, sprites and elves appear red, thanks to the abundance

of nitrogen in our atmosphere. But in Jupiter’s hydrogen-dominated atmosphere, these
phenomena likely appear pink or blue, as in this artist’s concept.

WWW.ASTRONOMY.COM 13

STRANGE UNIVERSE

The devil’s in the details

What should you really look for through the eyepiece?

This 2004 image of You’ve heard the cliché about details. But it’s Very cool, but not a fine-detail challenge, since
Saturn shows clearly
the Cassini division — celestially inaccurate, because details are observing them requires no more than a $5 toy telescope.
the dark gap between
the planet’s A and B where we usually discover the sublime — or, Sharp-eyed observers have even claimed to see them
rings. Spotting details
like this is what keep at least, they’re what lure our attention. So, what is it unaided. So if you did invest more than $5 and want to
us returning to the
eyepiece. NASA/JPL/SPACE that we crave to see, time and time again? “open ’er up” to see what the 440-horsepower engine

SCIENCE INSTITUTE For the sake of newbies who are just starting on this under your telescope’s hood will accomplish, you’ll want

BY BOB BERMAN epic adventure of exploring the universe, let’s more of a challenge.
Bob’s newest book,
Earth-Shattering help whittle down the long process of deciding But first, a reminder that whatever cosmic
(Little, Brown and
Company, 2019), where to look. Our theme this month is the Details are wonder you’re after, optics alone aren’t enough.
explores the greatest exquisite detail that, I guarantee, you’ll keep where we If someone gave you the keys to the two
cataclysms that have trying to observe. 6.5-meter Magellan Telescopes (along with the
shaken the universe.
For example, everyone enjoys watching usually instruction booklet explaining how to detach

Jupiter’s four big moons form a straight line discover the all 30 cables from the echelle spectrograph and
with military band precision. As giant sublime. instead insert a nice 30mm visual eyepiece),
Ganymede circles back to its starting point you’d still need a night of good seeing, or atmo-

once a week, Europa goes around exactly spheric stillness. Fine detail always requires

twice — to the second! And in that same good seeing. Where I live, excellent seeing

interval, Io completes four revolutions, again with conditions arrive as often as magnetic pole reversals. But

one-second accuracy. They’re bright, easy to see, and when they do come — heralded when stars are not twin-

unique. And no other planet with satellites shares kling in the least — we excitedly look for cool details.

Jupiter’s lack of axial tilt. Jove’s poles angle a negligible On Jupiter, that starts with the Great Red Spot, the

3° from vertical. And since its satellites orbit its equator, comically understated name for the universe’s largest

they must line up no matter where in their orbit they hurricane. (Official celestial names rarely serve as wor-

happen to be. thy observing suggestions.) Jupiter’s coolest features may

14 ASTRONOMY • FEBRUARY 2021

be the unnamed cloud details: Between its main dark ABOVE: NGC 7000,
belts, on the equator, diagonal white clouds contain also known as the
breaks where one can peer deeply down and see actual North America
blue sky, no joke. Some of us routinely seek out those Nebula, floats in the
amazing unnamed cobalt sky patches. upper left corner of
this image. Can you
On Saturn, most observers seeking fine detail first see the faint outline
try for the Cassini division. This inky gap between its of the continent for
A and B rings highlights the yawning breach separating which it is named?
the rings’ unique, epic beauty and their names, lazily
derived from the alphabet. We often give things letters, DENNIS HARPER
like the six stars in M42’s stunning Trapezium and lunar
craters around larger ones (Copernicus A, B, C, etc.). It’s LEFT: M51 (on the
not a bad idea, except where exceptional beauty cries right) is a face-on
out, unanswered, to try to stir a poet on the International spiral galaxy with
Astronomical Union’s naming committee. As for that prominent arms that
Cassini break, its impossibly narrow, half-arcsecond attentive amateurs
width somehow materializes whenever the air is steady. can glimpse through
In the entire universe, no other thin dark line is more the eyepiece.
observed, sought after, or treasured.
STEPHEN RAHN
You get the gist of my criteria. So, I’ll skip any further
literary flourishes and simply list 10 examples of details WWW.ASTRONOMY.COM 15
telescopists try for when observing various celestial
objects:

1 Mars: The polar caps and dark surface

markings

2 Orion Nebula (M42): Those six

Trapezium stars

3 NGC 4575: A silhouetted black dust

lane running this edgewise galaxy’s entire
length

4 M51: The galaxy’s two spiral arms

5 The Moon: Six craterlets forming a

French curve inside Clavius

6 Sirius: Its “Pup” companion star

7 M87: A single jet of near-light-speed

material issuing from the galaxy’s core

8 Mercury: The planet’s Moon-like

phases, slight orange color, and subtle dark
surface blotch

9 NGC 7000: The outline of North America

10 The Horsehead Nebula: Anything

resembling the knight from your chess set

But what about you? Is there some marvelous detail
you glimpsed long ago and have sought out ever since?
Some enchanting feature the rest of us should hunt for?
Share it! That’s the point of this column.

Let’s make it a contest — the winner gets to replace
the names of Saturn’s A and B rings with more inspira-
tional letters.

BROWSE THE “STRANGE UNIVERSE” ARCHIVE
AT www.Astronomy.com/Berman

An international fleet of spacecraft set off for
Mars, Crew Dragon carried astronauts to the ISS,
and a global pandemic left its mark on astronomy.

TOP 10

SPACE STORIES

OF 2020

BY ALISON KLESMAN AND JAKE PARKS Mars and Venus

2020 WAS A WILD YEAR. Astronomers kicked it off with 9 are geologically
the discovery of a distant galaxy group. Closer to home, they active
saw the Milky Way doing the wave and confirmed geologic
activity on Mars. The star Betelgeuse underwent a strange and ON FEBRUARY 24, 2020,
striking dimming event, while naked-eye Comet NEOWISE
took our breath away. And a major announcement about researchers released the initial
Venus sparked intense interest; that researchers are still scruti- results of NASA’s InSight lander on
nizing the result is a signal that science is working as it should. Mars. Covering the first 10 months
of the mission, the findings included
In May, SpaceX’s Crew Dragon capsule ferried astronauts to the conclusion that the Red Planet is
the International Space Station from U.S. soil, the first such seismically active.
trip in nearly a decade. Two months later, three new missions
launched for Mars to usher in a new era of robotic exploration. Of 174 marsquakes recorded from
February to September 2019, scien-
The global pandemic that defined much of the year changed tists traced two of the strongest to
how scientists worked and shuttered telescopes for months. But Cerberus Fossae. This young region
despite these challenges, our top 10 space stories show how we has undergone volcanism and other
pressed on with new, innovative ways to explore our universe. geologic changes in the last 20 million
to 2.5 million years, says Suzanne
Smrekar, deputy principal investiga-
tor for InSight. “Mars’ surface is on
average several billion years old, so
anything in the million-year range is

Earliest galaxy

10 group found
THE COSMIC Vithal Tilvi of Arizona State
University, who is part of EGS77 (circled in green) is the earliest galaxy group ever discovered. The inset
DARK AGES the Cosmic Deep And artist’s concept shows how these galaxies are blowing bubbles of ionized
Wide Narrowband (Cosmic hydrogen around them during the era of reionization. NASA, ESA AND V. TILVI (ASU)
began 380,000 years DAWN) survey seeking
after the Big Bang. At first, to understand this era. light-years across. These bub- team to spot fainter galaxies
no stars or galaxies existed Astronomers also aren’t sure bles overlap, creating a larger, than could be seen if they
to emit light. But even after how fast the transition from single region of space that’s were alone.
these objects began forming, an opaque to a transparent free of cosmic fog, allowing
their light remained shroud- universe occurred. light to travel freely. “So far we In the future, Tilvi says,
ed because the universe was had [seen] individual galaxies using the same technique will
filled with a “fog” of neutral Then the survey found spread across the survey areas. allow researchers to discover
hydrogen atoms that absorb EGS77: three galaxies shining This is the first time we have more faint galaxies. That will
and scatter ultraviolet light. 680 million years after the found a group of galaxies” ensure astronomers don’t
Big Bang, when the universe making the universe transpar- underestimate the number
Over time, energetic ultra- was just 5 percent its current ent, says Tilvi. By virtue of of dim galaxies — which we
violet light from early objects age. “[It’s] the most distant being in a group, EGS77’s know outnumber bright ones
ionized these hydrogen atoms, group of galaxies — and combined bubbles allowed the — responsible for bringing
knocking away their elec- therefore the earliest group of about cosmic dawn.
trons. This era of reionization galaxies in the universe — we
ended 1 billion years after the have ever seen,” says Tilvi,
Big Bang, leaving the universe whose team published their
transparent to light. find February 27 in The
Astrophysical Journal Letters.
But astronomers aren’t
sure exactly what types of Each galaxy is generating
objects — galaxies, black a bubble of ionized hydrogen
holes, or stars — were about 2 million to 3 million
responsible for clearing the
fog during reionization, says

super intriguing,” she adds. “Where’s the Cerberus Fossae is a young, features called coronae, which scientists think
energy [for the activity] coming from? Why geologically active region of Mars form when faults develop around areas where
there and not elsewhere on Mars?” responsible for at least two powerful rising magma lifts up the surface. By comparing
quakes detected by NASA’s InSight 3D models of how coronae form and evolve
By late September 2020, InSight had lander. ESA/DLR/FU BERLIN, CC BY-SA 3.0 IGO with observations of Venus’ surface, the team
recorded about 500 quakes, roughly 50 of concluded at least 37 of the planet’s large coro-
which give clues about the planet’s deep inte- The large, circular Aine Corona nae are still evolving — indicating the planet is
rior, Smrekar says. By studying how seismic dominates this Magellan radar geologically active.
waves travel through the lower crust, scientists image of Venus’ surface. New
have learned Mars’ crust is likely intact — research suggests dozens of these Smrekar — who is also principal investigator
“more like Earth’s than the Moon’s, where the features are still active on the of the Venus Emissivity, Radio Science, InSAR,
crust has been pummeled and fragmented by planet. NASA/JPL Topography & Spectroscopy (VERITAS) mis-
impacts,” she says. “Overall, we are seeing a sion currently under consideration for NASA
level of seismicity within the predicted range,” funding, and who worked on the Magellan
Smrekar concludes — except when it comes to spacecraft that orbited Venus in the early 1990s
bigger quakes, which are rarer than expected. — isn’t surprised. Despite the fact that the idea
“It may be that we just need to be patient, or of Venus as a geologically dead planet has per-
maybe Mars is behaving in a way that we sisted, she says, “There [have been] a bunch of
didn’t anticipate.” recent studies that point to current, geologically
recent activity on Venus.”
But Mars isn’t the only active inner planet.
On July 20, a paper in Nature Geoscience And research into Venus is gaining even
added evidence for recent volcanic activity on more momentum, as evidenced by No. 2 on this
Venus. Researchers led by Anna Gülcher at list. “I’m positive this will lead to great new sci-
ETH Zürich in Switzerland looked at circular ence,” Smrekar says.

WWW.ASTRONOMY.COM 17

Solar science enters

7 a golden age
ALTHOUGH THE CLOSEST STAR to
Earth has been widely studied, the Sun still
maintains some secrets. But perhaps not for
long, as a veritable armada of solar science missions
may soon unlock the last mysteries.
“In my opinion, the most interesting and signifi-
cant solar discoveries have been coming from the
Parker Solar Probe,” says Russell Howard, head of
the U.S. Naval Research Laboratory’s Solar and
Heliospheric Physics branch in Washington, D.C.,
and principal investigator for Parker’s Wide-field
Imager for Solar PRobe (WISPR). Parker, which
launched in 2018, “has been making both in situ and
remote sensing observations from … much closer
to the Sun than ever before.” Recently, the probe
revealed that the Sun’s magnetic field is surprisingly
complex far from the star. The simple dipole (like a
bar magnet) structure researchers expected is there,

Betelgeuse blows its
8 nose in our direction
IN LATE 2019, Orion the Hunter began

having shoulder problems: Betelgeuse,

the red giant star that marks the figure’s

right shoulder, started dimming dramatically.

While astronomers know the star varies regularly over

time, this episode was both unexpected and unusually SpaceX’s Crew
extreme, noticeable even to naked-eye observers. By Dragon capsule
mid-February 2020, the star was just one-third its normal prepares to
brightness and the astronomical community was abuzz — dock with the
could this signal an impending supernova explosion? International
Space Station
But, spoiler alert, Betelgeuse remains a fixture in our during the
night sky. It’s also back to normal brightness. So, what Demo-2
happened? An August 13, 2020, paper in The Astrophysical mission in this
artist’s concept.

Journal provides the explanation. Based on Hubble Space SPACEX

Telescope observations leading up to the so-called

“Great Dimming Event,” the authors concluded the star

“sneezed” out a cloud of hot gas from its photosphere in

fall 2019. By the time it reached millions of miles from the

star, the cloud had cooled and condensed into dust grains

that temporarily obscured the star’s southern hemisphere

and made Betelgeuse appear dimmer.

According to study leader Andrea Dupree of the

Harvard-Smithsonian Center for Astrophysics in

Cambridge, Massachusetts, events like this can A NEARBY SUPERNOVA?
show astronomers how stars like Betelgeuse lose

mass — a process that is poorly understood. Despite its continued presence, questions still abound about what

we’ll see when Betelgeuse does finally end its life in a brilliant

explosion. To observers on Earth, “all this brightness would be

In late 2019, Betelgeuse sneezed out a cloud of hot gas. Over concentrated into one point,” says University of California, Santa
the next few months, that gas condensed into dust that Barbara, astronomer Andy Howell, whose answer is based on
blocked a portion of the star’s light, as shown in this artist’s simulations run by two UCSB graduate students, Jared Goldberg and
concept. ESO, ESA/HUBBLE, M. KORNMESSER Evan Bauer. “It would be this incredibly intense beacon in the sky

that would cast shadows at night, and that you could see during the

daytime. Everyone all over the world would be curious about it,

because it would be unavoidable.” — Eric Betz, A.K.

18 ASTRONOMY • FEBRUARY 2021

SOLAR ORBITER/EUI TEAM/ESA & NASA; CSL, IAS, MPS, PMOD/WRC, ROB, UCL/MSSL Sun in mid-June. Its 10 instruments are working as expected
— or better, says Howard, who is also principal investigator
Solar Orbiter snapped this ultraviolet image of the Sun from halfway between of the Solar Orbiter Heliospheric Imager (SoloHI).
Earth and our star. It is the closest photo of the Sun ever taken.
SoloHI appears less affected by stray light than estimated
Howard says, but overlaid with other structures as well, and the magnetometer observed the signs of a coronal mass
which scientists are now modeling to better understand. ejection event. Ultraviolet images show never-before-seen
bright spots on the Sun. Small and ubiquitous, each is about
Soon to observe in tandem with Parker is the European a millionth to a billionth the size of a traditional solar flare.
Space Agency/NASA Solar Orbiter spacecraft. After launch- Researchers have christened them “campfires,” and suspect
ing February 9, 2020, the probe made its first close pass of the they are either miniature solar flares or perhaps related to
nanoflares, which are thought to heat the Sun’s outer atmo-
sphere, the corona.

The more sensors in the solar wind, the better, Howard
says, because that gives scientists a more comprehensive
view. Parker and Solar Orbiter are also joined by the Solar
and Heliospheric Observatory, the two Solar Terrestrial
Relations Observatory probes, the BepiColombo mission,
and the ground-based Daniel K. Inouye Solar Telescope.
“I am extremely excited about this ‘golden age’ of solar
observations from five different space probes and the
ground-based observations,” Howard says.

The launch, which was due to the detection of low

streamed online and aired levels of a potentially toxic

by all major TV news net- propellant called nitrogen

works, was viewed live by tetroxide. After it was

some 10 million people. The purged from the spacecraft,

following day, the spacecraft the astronauts safely exited

docked with the ISS and its the sealed crew cabin,

passengers, astronauts proving the privately built

Doug Hurley and capsule’s worth.

Robert Behnken, migrated to On November 15, the

the orbiting research first official Crew

lab, where they Dragon mission,

spent the next dubbed Crew-1,

two months blasted off for

testing Crew the ISS. After

Dragon and docking with

carrying out the space sta-

science tion the next

experiments. day, NASA

Once their stint NASA/JSC astronauts Michael

on the ISS concluded, the Hopkins, Victor Glover,

pair hopped back into Crew and Shannon Walker, as

Dragon and set course for well as JAXA astronaut

Crew Dragon ferries home. Shortly after 1:48 P.M. Soichi Noguchi, boarded

6 astronauts, a first CDT on August 2, Hurley the ISS, where, as of the

and Behnken splashed down time of this writing, they

in the Gulf of Mexico. The continue to work.

SINCE THE (ISS). But that’s not the case capsule was plucked from Now that two Crew

RETIREMENT anymore. In a historic first, the water by the recovery Dragon spacecraft have

of the Space Shuttle the private spaceflight com- ship Go Navigator shortly successfully delivered

Program in 2011, NASA pany SpaceX launched two thereafter. Out of an abun- astronauts to the ISS, the

astronauts have depended American astronauts into orbit dance of caution, the future once again looks

on Russia for rides to the May 30 as part of the Crew astronauts’ departure from bright for American crewed

International Space Station Dragon Demo-2 mission. Crew Dragon was delayed spaceflight.

WWW.ASTRONOMY.COM 19

LEFT: Comet NEOWISE’s twin tails
spread across the sky over West
Texas. Now on its way back to
the outer solar system, NEOWISE
won’t return for nearly 7,000 years.

JAMES LOWREY

A triple comet surprise eagerly awaited C/2019 Y4
(ATLAS), whose mid-May
5 WHEN IT WAS after its December 8, 2019, glow astronomers predicted
DISCOVERED perihelion pass. would be rivaled only by
Venus. But on April 11,
August 30, 2019, John Noonan of the amateur astronomer
Jose de Queiroz snapped
the second-known Lunar and Planetary a photo that showed the
comet breaking up. Hubble
interstellar visitor to our solar Laboratory at the University images on April 20 and 23
confirmed the comet had
system, Comet 2I/Borisov, of Arizona, Tucson, was part fragmented into several
pieces — an interesting turn
hadn’t yet made its closest of a team that observed of events for researchers,
but one that quashed any
pass to the Sun (called peri- Borisov with the Hubble chances of ATLAS achiev-
ing “great comet” status.
Our solar system’s second helion). Unlike 1I/2017 U1 Space Telescope in late
identified extrasolar visitor, ‘Oumuamua, which was spot- December and early January. Fortunately, C/2020 F3
Comet Borisov, appeared much ted only after it had already They looked for carbon (NEOWISE) stepped up. It
more cometlike than ‘Oumuamua. rounded our star, astrono- monoxide (CO) sublimating, flared to naked-eye visibility
This Hubble image was snapped mers were able to watch or turning directly from solid between magnitude 1 and 2
shortly after Borisov made its after rounding the Sun on
closest approach to the Sun in July 3, just over three months
after its discovery. The comet
December 2019. NASA, ESA AND Borisov before, during, and ice to gas, off the surface. quickly developed a pictur-
“[CO] sublimates at very low esque pair of gas and dust
D. JEWITT (UCLA) tails that ultimately stretched
more than 30° across the sky
temperatures. So, if you see and offered an ideal target
for astrophotographers.
carbon monoxide, that tells
NEOWISE spent several
THE COVID-19 PANDEMIC you something has been cold weeks delighting skywatch-
for a very long time,” he says. ers as the brightest Northern
Hemisphere comet since
The coronavirus pandemic impacted astronomy in 2020 in many On Borisov, “there was C/1995 O1 (Hale-Bopp).
ways, from major observatories shuttering their scopes to mass more carbon monoxide than “What a great little comet!”
astrophotographer John
transitions to remote work. More than 100 of Earth’s largest tele- there was water, which is Chumack wrote in an email
on July 29 to Astronomy.
scopes closed at some point during the year. Jet Propulsion pretty much unheard of” for By then, the comet was a
Laboratory engineers, unable to take their high-performance com- comets in our own solar sys- 4th-magnitude target low in
puters and virtual reality setups out of the lab, drove Curiosity on tem, Noonan says. The the northern sky. “Over the
Mars from home using plastic red-blue 3D glasses to visualize the out-of-whack ratio means last few weeks, NEOWISE
rover’s complex environment. And scientists launching missions put on a nice show for us
Northern Hemisphere
such as Solar Orbiter and Mars 2020 faced unique challenges Borisov “very clearly formed observers. Some of my
astronomy friends in the
imposed by travel restrictions to reduce the spread of disease. in a system … very different Southern Hemisphere have
Fall 2020 saw a rash of telescope reopenings as conditions in than our own.” That place now got to glimpse it and
could have been around a red they are reporting it still
some locations improved. The Very Energetic Radiation Imaging dwarf star — stars smaller fading,” he said.
Telescope Array System in Arizona and the Las Campanas
Observatory in Chile had reopened by October 8.

Telescopes at Kitt Peak in Arizona, and Cerro and cooler than our Sun, and

Pachón and Cerro Tololo in Chile, also began SARAYUT THANEERAT/DREAMSTIME commonplace throughout
reopening at that time. By late October, the the galaxy.
Atacama Large Millimeter/submillimeter
Array was also readying for reopening As Borisov faded from
and a new round of South Pole headlines, comet enthusiasts

Telescope observers had gone into

quarantine to prevent carrying the

virus to Antarctica. — A.K., E.B.

20 ASTRONOMY • FEBRUARY 2021

4 First midsized black hole detected FAST FACTS
BLACK HOLES COME in scientists at the Laser Interferometer
a variety of sizes, ranging Gravitational-wave Observatory (LIGO) Stellar-mass black holes:
a few to 100 solar masses
from a few to billions of times and the partnering Virgo site received
Intermediate-mass black holes:
the mass of the Sun. Although the first convincing sign: gravitational 100 to 1 million solar masses

there is ample evidence for stellar-mass waves that point to the violent birth of Supermassive black holes:
millions to billions of solar masses
and supermassive black holes, there is an intermediate-mass black hole (IMBH).
85 solar masses, so the larger one firmly
surprisingly little proof of their middle- After spending more than a year scru- falls in the “pair-instability mass gap.”
When most massive stars die, they leave
weight brethren. But on May 21, 2019, tinizing the signal (called GW190521), behind a black hole. But when a star
weighs 130 to 200 solar masses, photons
which lasted just a tenth of a second, on in its core become so energetic they
morph into electron-antielectron pairs,
An IMBH is born September 2, 2020, an international team which can’t fully combat gravity. The star
of researchers released two papers detail- becomes extremely unstable and, after
going supernova, leaves nothing behind.
ing their results: The gravitational waves
“This event opens more questions
originated halfway across the universe and than it provides answers,” LIGO member
Alan Weinstein, professor of physics at
were produced when two hefty black holes Caltech, said in a press release. “From the
perspective of discovery and physics, it’s a
GW190521 merged to create an IMBH about 142 very exciting thing.”

times the mass of the Sun. Their collision

GW150914 also released a stupendous amount of

energy, equivalent to roughly eight solar

GW170608 masses, as gravitational waves.
Although this detection confirms that

IMBHs exist, it also raises questions. The

GW190814 progenitor black holes weigh in at 66 and

GW190521 signaled the birth of an intermediate-
mass black hole. But it didn’t sound like a typical
“chirp” — it was more like a “bang.” D. FERGUSON, K. JANI,

D. SHOEMAKER, P. LAGUNA, GEORGIA TECH, MAYA COLLABORATION

The Milky Way does the wave star-forming regions that make up the Wave. That work
involved combining observations of the way intervening dust
3 BECAUSE WE ARE EMBEDDED within the and gas makes starlight appear redder with accurate distance
Milky Way Galaxy, mapping its large-scale struc- measurements to those stars from ESA’s Gaia spacecraft.
ture is challenging. That is especially the case for
galactic star-forming regions, huge clouds of gas “Since this effect [reddening] is observable throughout our
and dust whose distance is difficult to measure because solar neighborhood, it allowed us to determine the distances
they aren’t points like single stars. But new work by Harvard to a huge sample of star-forming regions, using the same
University astronomers published January 7, 2020, in Nature technique, for the first time,” Zucker says. “Previous distance
dramatically increased the accuracy of distance measurements techniques were piecemeal, obtained inhomogeneously on a
to nearby star-forming regions. It also uncovered something cloud-by-cloud basis.”
unexpected: the Radcliffe Wave.
Her technique revealed, to a factor of five times better
Nearly 9,000 light-years long and 400 light-years wide, this than previous measurements, the distances to nearby
snaking line of interconnected star-forming regions rises above star-forming regions — and the Radcliffe Wave. “In the
and dips below the plane of our galaxy. It lies less than 500 future, this will force us to reframe our understanding of star
light-years from Earth at its nearest point and connects molec- formation on small scales (i.e., within individual molecular
ular clouds in Orion, Taurus, Perseus, Cepheus, and Cygnus. clouds) in a larger galactic context,” she says.

“Prior to the discovery of the Radcliffe Wave, star-forming
regions were studied in relative isolation. The Radcliffe Wave
showed that all these regions are connected on the grandest
of scales, via tendrils of filamentary gas, which is something
we never knew before,” says Catherine Zucker, whose Ph.D.
work at Harvard led the effort to pin down distances to the

The Radcliffe Wave (shown in red; the location of our Sun appears in yellow) is
a sinuous structure thousands of light-years long and hundreds of light-years
wide. It connects several star-forming regions and likely forms the densest part
of the spiral arm in which the Sun resides. IMAGE FROM THE WORLDWIDE TELESCOPE, COURTESY OF

ALYSSA GOODMAN

Researchers think 1
they’ve detected signs
of a biosignature, Missions to
phosphine (left), in
Venus’ clouds. But that MARS
claimed detection has
since come under
heavy scrutiny. ASTRONOMY:

ROEN KELLY; ALMA (ESO/NAOJ/NRAO),

GREAVES ET AL. & JCMT (EAST ASIAN

OBSERVATORY)

Astronomers spy phosphine on Venus AS USUAL,

2 VENUS IS A SIZZLING others remain skeptical. Chemical com-
world thought by many pounds each have a unique spectrum, or THE RED

to be inhospitable to life. fingerprint, that depends on the wave- PLANET

Surface temperatures are lengths of light they absorb. Although the has had quite HOPE
hot enough to melt lead — almost researchers detected this fingerprint of a year. Not only

900 degrees Fahrenheit (480 degrees phosphine with two independent tele- did NASA’s InSight lander detect

Celsius) — while the pressure at scopes at different times, they only saw it hundreds of marsquakes shaking

ground level is more than 90 times that at a single wavelength — one that sulfur the planet, but ESA’s Mars Express

of Earth at sea level. But that hasn’t dioxide happens to absorb as well. orbiter found more signs that the

stopped some, including Carl Sagan, “As a geochemist, I always worry world has several underground

from proposing that life could exist about detection from one peak,” says saltwater lakes buried beneath its

in the more temperate clouds of our Justin Filiberto of the Lunar and south pole. Perhaps most impor-

sister planet. And now, there could be Planetary Institute. “A single line is a tantly, however, 2020 saw three

evidence to support that hypothesis — coincidence, not a detection,” adds new spacecraft set forth for the

albeit controversial evidence. astrobiologist Kevin Zahnle of NASA Red Planet, taking advantage of a

In a paper published September 14 Ames Research Center in California. Still once-every-26-months alignment

in Nature Astronomy, researchers pre- others are concerned about the quality that shortens the time and distance

sented observations of an inexplicable of the noisy data itself, which means required to get from Earth to Mars.

surplus of the rancid gas phosphine in many groups are already reanalyzing it. As its first interplanetary mis-

the clouds of Venus. On Earth, microbes But if the detection holds up, “it sion, the United Arab Emirates

produce most phosphine, though it can demands follow-up,” says Bethany launched an orbiter named al-Amal

also be created abiotically under great Ehlmann, a planetary scientist at Caltech (meaning “Hope”) July 19. The craft

temperatures and pressures. Measured who was not part of the discovery team. is equipped with both an infrared

at a level of some 20 parts per billion, “The top three destinations to look and ultraviolet spectrometer — the

the researchers behind the new paper for life in the solar system are Mars, former meant to investigate dust,

say no known geological activity or Enceladus, and Europa — and now we

exotic catalysts — such as lightning or should perhaps add Venus to the list.”

meteorites — can explain the strength

of their observed signal.

“We are not claiming we have found Stories to watch for in 2021
life on Venus,” said co-author Sara

Seager, an MIT planetary scientist, in a

press conference. However, she added, The missions NASA’s Double Because of
they can’t explain the phosphine’s origin. that left Earth Asteroid Redirection technical
for Mars in 2020 Test, or DART difficulties and
Many find the unexplained biosig- — the UAE’s mission, will launch the ongoing
nature, or potential evidence for past Hope, China’s July 22, 2021, to binary coronavirus
or present life, tantalizing. However, Tianwen-1, asteroids Didymos pandemic, NASA

and NASA’s and Dimorphos. has updated its

Alison Klesman and Jake Parks are Perseverance The agency’s Lucy target launch date
associate editors of Astronomy. They sure — will all reach spacecraft is scheduled for the James
hope 2021 is better than 2020. the Red Planet in to launch October 16, Webb Space
February 2021. 2021 — the first mission Telescope to

to Jupiter’s Trojan October 31, 2021.
asteroids.
22 ASTRONOMY • FEBRUARY 2021

Three Mars missions from
three different countries took
advantage of an alignment
between Earth and the
Red Planet in 2020. The
missions will teach us more
about Mars’ atmosphere, seek
out signs of past and present
life, and even cache rock
samples for their future return
to Earth. NASA/JPL-CALTECH

water, and ice in Mars’ lower atmo- present life. Then the orbiter will enter a TIANWEN-1 ALL ILLUSTRATIONS: ASTRONOMY: ROEN KELLY
sphere and the latter meant to study polar elliptical orbit around Mars.
oxygen and carbon monoxide in the There, it will serve as a communica- life once existed in Mars’ Jezero Crater.
upper atmosphere. Additionally, the tion relay for the rover and lander, as The rover also comes with a few proof-
craft carries a multiband camera that well as use its seven science instruments of-concept experiments: an oxygen-pro-
can achieve resolutions better than to remotely study Mars’ environment duction device called MOXIE and a
5 miles (8 kilometers) per pixel. and map its surface. solar-powered helicopter named
Altogether, Hope aims to paint a more Ingenuity. Last but not least, Perseverance
comprehensive picture of the Red Finally, on July 30, NASA launched plans to find, collect, and seal rock and
Planet’s atmosphere. the Perseverance rover as part of its Mars soil samples that will ultimately be
2020 mission. This car-sized rover, based returned to Earth for closer inspection
China jumped into the fray next, largely on Curiosity’s design, has ambi- with sophisticated lab equipment.
launching an orbiter, lander, and rover tious plans. Equipped with instruments
trio to Mars July 23. Tianwen-1 (which that can create spatial maps showing the With all these missions expected to
means “heavenly questions”) is the reach the Red Planet in February, 2021
country’s first fully homegrown Mars elemental and mineralogical com- is bound to be a big year for Mars.
mission. Engineers plan for the orbiter position of rocks, Perseverance
to release the lander/rover combo will seek evidence that ancient
after a few months orbiting the
Red Planet. It will touch down PERSEVERANCE
near Utopia Planitia in the
northern hemisphere to
seek signs of past or

Also delayed due The ESA and First light for the Both the Parker The uncrewed
to coronavirus, Roscosmos’ robotic 8.4-meter Simonyi Solar Probe and Artemis I mission,
the Indian Luna-25 lander Survey Telescope Solar Orbiter will the first in NASA’s
Space Research aims to put Russia at the Vera C. Rubin make flybys of plan to return
Organisation’s back on the Moon Observatory in Venus in 2021: humans to the
Chandrayaan-3 with an anticipated Chile is expected Parker will make Moon, is scheduled
mission, which launch date in in October 2021. two, Solar Orbiter to launch in 2021.
comprises a October 2021. will make one. This first mission
lander and rover, will combine the
is now scheduled new Space Launch
to launch for the System rocket and
Moon in late 2021. Orion crew capsule.

NEW MARS
ROVER

begins its mission

24 ASTRONOMY • FEBRUARY 2021

Perseverance is more than just Curiosity’s
double — it will hunt for ancient life,
cache samples, and pave the way for
human explorers. BY JIM BELL

EVERY 10 YEARS, planetary scien- collectively known as Mars Sample Perseverance takes its first driving test on
tists put their collective minds together Return. December 17, 2019, in a clean room at NASA’s Jet
to develop mission recommendations Propulsion Laboratory in Pasadena, California.
for the decade ahead. The most recent of Now, nine years later, that
these decadal surveys, published in 2011, ambitious journey is about to begin. NASA/JPL-CALTECH
had a clear top priority for NASA: to The Mars 2020 mission launched from
collect samples from the surface of Mars Cape Canaveral on July 30, 2020, and is Perseverance lifts off on July 30, 2020, atop a
and return them to Earth. scheduled to land in Jezero Crater on United Launch Alliance Atlas V rocket at the
February 18, 2021. If all goes well, the Space Launch Complex-41 on Cape Canaveral.
The concept of returning samples rover will embark on a mission lasting
from Mars has been something of a holy at least a full martian year (equivalent UNITED LAUNCH ALLIANCE
grail for planetary scientists. As intrepid to 687 days on Earth). In addition to its
as NASA’s previous robotic explorers own explorations, it will also collect and
have been, their analyses of the rock and cache samples that will later be returned
soil they rove have always been limited to Earth — revealing the mysteries of
by the equipment they carry. When you that once-habitable place on Mars.
ship a rover to Mars, the cost of every
extra ounce is colossal. And rover A clone is born
instruments — marvels of engineering
though they are — are no substitute for In December 2012, just four months
a fully equipped laboratory on Earth. after the Curiosity rover landed
on Mars, NASA announced a new
That’s why, in the 2011 Decadal wheeled explorer that would address
Survey, scientists recommended NASA the top goal of the most recent decadal.
design a flagship mission to “collect, It was scheduled to launch during a
document, and package samples for favorable Earth–Mars alignment in
future collection and return to Earth.” 2020. This Mars 2020 rover would
In other words, the community be designed and built by a team at
strongly recommended that NASA NASA’s Jet Propulsion Laboratory
finally greenlight a set of missions (JPL) in Pasadena, California — a team
that included many of the engineers,
The Perseverance rover is NASA’s follow-up to the managers, and others who had built
successful Curiosity rover and will rove Jezero Curiosity, as well as previous Mars rov-
Crater in search of chemical or textural evidence ers Sojourner, Spirit, and Opportunity.
of past microbial life. NASA/JPL-CALTECH
To fit NASA’s tight budget and
reduce the mission’s complexity,
90 percent of the Mars 2020 rover,
cruise stage, and sky crane landing
system would be built from spare parts
left over from Curiosity. Mars 2020

With social distancing in effect, senior engineers
in Southern California conducted their final
inspections remotely via a video feed from a
smartphone at the Kennedy Space Center in
Florida. NASA/JPL-CALTECH

MARS SAMPLE RETURN

WHILE NO MISSIONS have yet been approved or funded, several space agencies around A ROVER’S
the world are deep in the planning stages for a Mars sample-return mission. For example, JOURNEY

NASA and the European Space Agency (ESA) are discussing a concept for joint missions Midway

that would find, collect, and return the samples cached by the Perseverance rover. And the

Chinese National Space Agency is looking into potential robotic sample-return missions as

follow-ons to their Tianwen-1 mission, which launched July 23, 2020, and will land a rover in

the Utopia Planitia region of Mars in February 2021.

The NASA/ESA plan as currently envisioned would involve the launch of two missions in

2026. The first is a dedicated NASA lander carrying an ESA-built “fetch” rover and a small

rocket known as the

Mars Ascent Vehicle

NASA sample ESA Earth 6 (MAV). The fetch rover
retrieval lander Return Orbiter would collect the cached
rocket rocket ERO travels to sample tubes left by
near-Earth orbit Perseverance on Mars’
and releases the surface and bring them
samples to Earth. back to the MAV, placing

5 them inside a soccer
ball-sized sample cap-
ESA’s Earth Return sule. The MAV would
Orbiter (ERO) picks then launch them into
up the samples.

Mars orbit, where an

4 ESA Earth-return orbiter
— the second launch of
The Mars 2026 — would be waiting
Ascent Vehicle to capture the sample
(MAV) capsule. That orbiter
launches the would then depart Mars
sample tubes and return to Earth, jetti-
into Mars orbit.

soning the capsule for a
3 parachute-assisted land-

The fetch rover ing in the Utah desert in

places the 2031. — J.B.

tubes inside an

ascent vehicle.

12

Perseverance collects the ESA’s “fetch” rover
samples and deposits them carries the tubes to the
in tubes on the ground. sample retrieval lander.

ASTRONOMY: ROEN KELLY. SPACECRAFT MODELS: NASA, ESA

would thus be a clone, of sorts — looking and weather of its field site. However, This map shows a hypothetical course that
a lot like Curiosity on the outside, but Perseverance also has a number of new and Perseverance might take, based on scenarios plotted
costing at least $700 million less than unique objectives. Perhaps the most impor- by mission scientists. The actual route will of course
Curiosity’s $2.8 billion price tag. tant is to seek the signs of ancient life. differ, depending on where Perseverance happens
to touch down within the landing ellipse. The prime
On the inside, however, the Mars 2020 Ancient means not focusing on any mission is to explore Jezero Crater; if the rover survives
rover would sport some entirely new potential living organisms on the surface to tackle an extended mission, it may trek up and out
equipment to help it carry out the sample- of Mars today (which are highly unlikely of the crater west to another site, dubbed Midway.
caching job the decadal had outlined. to exist, given the harsh radiation, low
The mission’s announcement kicked off surface pressure, and frigid temperature). ASTRONOMY: ROEN KELLY. BASE MAP IMAGE: ESA/FU-BERLIN; ROVER PATH (PRIME
what NASA Associate Administrator for Instead, Perseverance will seek evidence MISSION): SANJEEV GUPTA AND BRIONY HORGAN; ROVER PATH (EXTENDED MISSION):
Science John Grunsfeld called “seven of organisms that may have lived billions RICHARD OTERO, ERISA STILLEY, NATHAN WILLIAMS, ALLEN CHEN, ET AL.
years of innovation” to develop that of years ago, during a time early in Mars’
equipment, along with some completely history when the surface environment was ago, back in the Precambrian era, organ-
new tools. In early 2020, nearing the end a lot more like Earth’s. isms didn’t develop shells or skeletons that
of the seven-year sprint, the rover finally could easily leave behind fossil remains
received its name: Perseverance. These signs could come in the form of until about 550 million years ago.
preserved physical or chemical evidence,
In search of ancient life or textures left imprinted on rocks. Among the prime examples of ancient
Finding these biomarkers, however, is biomarkers on Earth are stromatolites,
Many of the Mars 2020 mission’s goals no small task. Geologists have a similar
are similar to those of previous Mars struggle on Earth: Though life began on
rover missions, like studying the geology our planet some 3 billion to 4 billion years

26 ASTRONOMY • FEBRUARY 2021

Delta Delta
remnants
Delta
surface

Crater Delta
rim base

Western Eastern
landing site landing site

Lake Jezero Crater
margin

landing ellipse

Crater floor

N

W
Prime mission
Extended mission
2 miles

3 kilometers

which are rock and mineral structures geological or geochemical processes. This reconstructed mosaic view of Jezero Crater’s
built up by coordinated groups of simple Rather, samples must often be taken back magnificent river delta from above looks west, out to
single-celled organisms, especially cya- into sophisticated laboratories with the the crater rim. The steep slopes of the delta in the
nobacteria (formerly called blue-green most advanced equipment that exists. foreground stand up to 350 feet (107 m) above the
algae). Finding structures like those in crater floor. NASA/MSSS/USGS
ancient rocks on Mars would be an excit- This is one of the main motivations
ing and potentially profound discovery. for making Mars 2020 the first step of an
international Mars sample-return pro-
But definitively confirming these gram. Barring the unambiguous (and
structures will be difficult with unlikely) discovery of biomarkers like
Perseverance’s toolkit alone. Taking a fossils, the only way to confirm signs of
cue from terrestrial geologists, planetary life might be to bring those samples back
scientists have realized that equipment to Earth so they can be studied in much
used in the field often cannot tease out greater detail. As Carl Sagan famously
whether the samples truly provide evi- noted, “extraordinary claims require
dence of biological action, or only extraordinary evidence.”

WWW.ASTRONOMY.COM 27

On September 4, while Perseverance was en route uncovered outcrop rocks with interesting landings sites have to meet certain engi-
to Mars, JPL moved the rover’s twin — a full-scale silica-bearing minerals and nodular neering requirements: close enough to
engineering model dubbed OPTIMISM (Operational shapes a decade earlier; some researchers the equator to avoid extreme cold; low
Perseverance Twin for Integration of Mechanisms think these are potential biosignatures, enough in elevation that a descending
and Instruments Sent to Mars) — to its “Mars Yard” as similar features can be found in some rover’s parachute has thick enough air
test area. Engineers can test rover commands and places on Earth. to grasp; and free enough of large rocks,
operations using OPTIMISM in an environment that slopes, and other potential obstacles to
simulates the Red Planet to better understand what The other three sites all sat within less avoid crashing into them.
Perseverance is experiencing on Mars. NASA/JPL-CALTECH than 100 kilometers of each other. Two of
them, near the famous dark region Syrtis But sites with large rocks and slopes
Mars 2020 also has a number of new Major, had abundant deposits of clay and are often some of the most scientifically
experiments that are designed to help carbonate minerals, potentially indicat- rewarding landscapes. So, clever engi-
engineers develop technology for future ing an ancient habitable environment. neers from JPL and elsewhere have
robotic and human Mars missions. For The final option was Jezero, a 31-mile- worked to develop more intelligent soft-
example, the rover carries a device wide (50 kilometers) impact crater on ware to guide Perseverance’s landing
designed to extract small amounts of the western margin of Isidis Planitia stage to a touchdown in Jezero Crater.
oxygen (O2) by splitting carbon dioxide that hosts clays, carbonates, and a well- One upgrade makes the descent stage
(CO2) molecules with electricity. Larger exposed ancient river delta. more aware of when and where to deploy
systems based on this technology could its parachute. And once the parachute
generate oxygen for future human crews The workshop participants and Mars is jettisoned and the rover and descent
on Mars. 2020 science team ultimately recom- stage are in powered retrorocket flight, a
mended Jezero — named after a small new hazard-avoidance system helps avoid
Perhaps Perseverance’s most famous town in the Balkan nation of Bosnia- rocks and other large obstacles, guiding
tech demo is a small four-blade helicop- Herzegovina — as their top choice, and the rover to a height of about 25 feet
ter drone named Ingenuity. Early in the NASA officially chose the site as the win- (7.6 meters) over a safe landing site.
mission, engineers will program it to ner in November 2018. Then, the sky crane system — pioneered
conduct three to five test flights to learn by Curiosity — lowers the rover to the
more about operating drones on Mars. Jezero will be among the most chal- ground via cables for a soft touchdown.
On future missions, such drones could lenging martian terrains that NASA
serve as scouts or sample delivery has yet attempted to land on. All rover
systems.
Jezero will be among the most challenging
Choosing a target martian terrains that NASA has yet
attempted to land on.
From 2014 to 2018, NASA and the plane-
tary science community carefully studied The experimental helicopter drone
options for where to land Perseverance. Ingenuity will become the first
Just as for previous NASA rover mis- aircraft to take powered flight on
sions, a series of open community work- another world. Though it won’t be
shops brought together scientists, JPL able to wander far — it will stay
mission engineers, technology experts, less than 0.6 mile (1 km) from the
and even members of the general public Perseverance rover to remain in
to discuss and debate which site would wireless communication (right) —
offer the best chance of accomplishing future drones could serve as more
the mission’s goals. capable scouts. At left, Ingenuity
receives its final inspection at the
By the time of the fourth workshop in Kennedy Space Center in Florida
October 2018, the competition had boiled before being mounted to
down to four sites. One option was a Perseverance for its journey
return to the Columbia Hills in Gusev to Mars. NASA/JPL-CALTECH
Crater, where the Spirit rover had

28 ASTRONOMY • FEBRUARY 2021

A crater to explore In the spring of 2020, as the COVID-19 pandemic took hold around the world, mission staff persevered and
adapted to working from home in the runup to the Mars 2020 launch on July 17. Clockwise from upper left:
When Perseverance takes in the land- lead mobility systems engineer Rich Rieber (with son Ben); deputy project scientist Katie Stack Morgan;
scape inside Jezero Crater for the first mission system verification and validation supervisor Ruth Fragoso; mission design and navigation manager
time, it will send back images that show Fernando Abilleira (below mission logo); staff assistant Monica Hopper; systems engineer Heather Bottom;
the hills of the crater rim rising 2000 feet project chief engineer Adam Steltzner; guidance and control systems engineer Swati Mohan; Entry, Descent
above the crater floor. If the rover lands and Landing phase lead Al Chen (with son Max); project manager John McNamee; and Entry, Descent and
close enough to it, early images could Landing systems engineer Cj Giovingo. NASA/JPL-CALTECH
also show the 150- to 350-foot-tall edge
of one of the most exciting aspects of A major goal of the mission is to drive size of the grain particles, and how
Jezero: its beautiful western river delta. the rover up to and perhaps even onto quickly the sediment builds up. The rover
that delta, to search for geologic, miner- team could try to systematically explore
On Earth, deltas are fan-shaped splays alogic, and chemical evidence of its past the equivalent of these different zones on
of sediments where rivers gently deposit environs. On Earth, different kinds of Jezero. This strategy could maximize the
sand and silt, forming layers of sand- traces of life can appear in different areas chances of finding regions where poten-
stone and mudstone that can trap and of a river delta depending on the speed of tial biosignatures might be preserved.
preserve organic materials. Jezero Crater the water that deposits the sediment, the
preserves several deltas along its inner After exploring and sampling the
rim, showing that it was clearly a shallow delta, the team might drive the rover to
crater lake sometime early in Mars’ his- the foothills at the boundary of the crater
tory. If life emerged on Mars long ago, floor and rim, where orbital measure-
evidence of it might be preserved in ments show a “bathtub ring” of clay and
those delta sediments. carbonate minerals — indicators of a past
watery environment that dried out as the
What that lake looked like billions of lake waters receded. From there, the team
years ago remains unknown, but there might drive the rover up the crater rim
are many possibilities. Perhaps waves — charting a course along the safest
were lapping at its shores, around what is slopes — to more closely explore the orig-
now the crater rim. Or, if the climate was inal ancient rocks from which the delta
too cold for surface water, Jezero may sediments originated.
have been a vast frozen expanse, with all
the river and delta-building action hap- If the rover team can successfully get
pening below. It’s tempting to speculate, Perseverance completely out of Jezero
but instead of making wild guesses, the Crater, just 10 miles (16 kilometers)
best recourse is to go there and find out. beyond the western rim lies one of the
rejected landing sites, dubbed Midway.
It’s also rich with ancient clay and car-
bonates, but many of those mineral
deposits could have been created by
groundwater coursing through the rocks,
rather than surface water. The chance to
explore a very different, but also poten-
tially once very habitable, ancient mar-
tian environment as part of an extended
mission is an exciting prospect.

WWW.ASTRONOMY.COM 29

PERSEVERANCE’S TOOLKIT Caching the samples

NASA SELECTED PERSEVERANCE’S scientific payload of six instrument systems in Of course, Perseverance’s scientific
a competition between dozens of proposals that researchers submitted in 2014. The legacy will also depend on the samples it
winners include three instruments on the rover’s mast: a pair of panoramic, zoomable collects for return to Earth. To perform
3D cameras called Mastcam-Z; a camera and spectrometer called SuperCam that this task, the rover’s designers carved
zaps rocks and soil with a laser to analyze their chemical makeup; and a weather- out a significant amount of space for the
monitoring station called the Mars Environmental Dynamics Analyzer (MEDA). For the Sampling and Caching Subsystem (SCS).
most part, these are enhanced versions of systems on the Curiosity rover. However, in The SCS drill, mounted on the rover’s
a first, SuperCam includes a high-fidelity microphone designed to record sounds on arm, will take core samples of martian
Mars — either from the instrument and other rover subsystems, or potentially from the rock and soil. Its carousel of bits includes
winds of Mars itself. six bits for drilling rock core samples,
one “regolith” bit for collecting soil, and
The rover carries three new science investigations as well. A ground-penetrating two abrading bits for grinding rocks
radar system called the Radar Imager for Mars’ Subsurface Exploration (RIMFAX) will or other surfaces for analysis with the
probe underground layers of rock — and potentially water ice. The Planetary rover’s instruments. There’s also a tool
Instrument for X-ray Lithochemistry (PIXL) will analyze samples on microscopic that can blow puffs of nitrogen gas onto
scales by focusing a beam of X-rays and taking images of the resulting glow. And an a sample to remove dust or drill tailings.
instrument called Scanning Habitable Environments with Raman and Luminescence
for Organics and Chemicals (SHERLOC) will put samples under a magnifying glass, The rover also houses a tiny robotic
so to speak, with a microscopic imaging subsystem called Wide Angle Topographic arm that can capture samples delivered
Sensor for Operations and eNgineering (WATSON). Together, the pair of devices will into the rover’s body, document them,
use an ultraviolet laser and spectrometer to search for biomarkers in organics and seal them in titanium tubes, and then
minerals. PIXL, SHERLOC, and WATSON are all mounted on the rover’s hefty robotic drop them onto the surface for later col-
arm; RIMFAX is mounted to the rover’s lower aft deck. lection and return to Earth. Perseverance
is carrying a total of 43 of these dry-erase-
In addition to its science instruments, Perseverance is outfitted with engineering- marker-sized tubes to Jezero. During the
focused cameras and other subsystems. These include cameras for basic navigation, prime mission, the science team hopes to
as well as front- and rear-mounted cameras for avoiding hazards. There are also seven fill up to 38 of them with the most com-
simple, largely “off-the-shelf” cameras mounted on the rover and the spacecraft stages pelling and potentially revealing rock
that will carry it to the surface. These will record images and video of the landing pro- and soil samples as possible.
cess. And, for the first time, there will be sound to go with it — a microphone will be
recording audio during the landing. In all, Perseverance, its descent stage, and the However, the remaining five are just
Ingenuity helicopter are loaded with 25 cameras, making it the most photo-capable as critical: They are specifically designed
spacecraft ever sent to the Red Planet. — J.B. to provide “witness samples” that charac-
terize any organic or other chemical
NaDCams SuperCam
Mastcam-Z WATSON
Rear SHERLOC
HazCams MEDA
PIXL
RIMFAX

MOXIE Front HazCams

NASA/JPL-CALTECH; ASTRONOMY: ROEN KELLY

30 ASTRONOMY • FEBRUARY 2021

contaminants that might have been HITTING THE MARK
brought to Mars from Earth, despite the
team’s best efforts at sterilizing the sam- MARYLAND Baltimore
ple tubes. Instead of being filled with
samples, they will go through a full WV
“mock coring” process and be handled
and sealed by the rover’s SCS systems just 2022 ExoMars 2020
like the actual samples. This provides a 120 × 19 km Perseverance
way to check whether any organic mate- 13 × 7 km
rials or other contaminants coming from
the rover itself have been able to sneak Annapolis
into the actual Mars samples, too.
2008 Phoenix 2012 Curiosity
Ready to rove 100 × 19 km 19 × 6.5 km

After several years of design, the rover Washington D.C.
instruments and subsystems finally
began taking shape in 2016. Engineers at 2004 Spirit
JPL assembled the rover in 2019 and put
it through extensive tests through the and Opportunity 2018 InSight
first half of 2020, simulating the harsh
thermal conditions on Mars and the 150 × 19 km 130 × 27 km Chesapeake Bay
vacuum of space.
VIRGINIA 1997 Pathfinder
The final stages of assembly, testing, 201 × 71 km
and installing the craft atop the launch 1976 Viking
vehicle occurred in the midst of the 280 × 100 km 20 30 miles
COVID-19 pandemic. By mid-April, 0 10
90 percent of the team at JPL was working
from home, but mission-critical personnel 0 25 50 kilometers
were still needed to at the Kennedy Space
Center in Florida to prep the rover itself. The landing ellipse is the area in which mission planners estimate a lander could touch down — i.e., the
margin of error they must account for. Improvements to Perseverance’s landing system make its landing
Following clean protocols was not a ellipse smaller and allow engineers to consider targeting more challenging and scientifically interesting
challenge for the team, as those are nec- terrain. This figure compares the landing ellipses of several Mars missions plotted over the more familiar
essary for preparing any lander to avoid territory of Washington, D.C. ASTRONOMY: ROEN KELLY, AFTER PAJOLA ET AL. (2019)
contaminating the worlds they visit. But
they improvised to minimize the number This aluminum plate bearing the staff of Asclepius — the Greek deity of healing and medicine — was
of people needed inside the clean room installed on the rover to commemorate the impact of the COVID-19 pandemic and to pay tribute to health
itself. For instance, the final “walkdown” care workers. NASA/JPL-CALTECH
inspection of the spacecraft — in which
experts in each spacecraft system give and issues related to COVID-19. Mars. And many of us are eagerly look-
the rover one last check — took place Considering the cost overruns that have ing forward to the day when we can see
remotely, with a technician in Florida plagued many past NASA flagship-class those rover-collected samples — not just
using a smartphone to send a video feed missions, a 12-percent overrun could be through the lenses of our sophisticated
to senior engineers at their homes. considered something of a minor victory. robotic avatar, but with our own human
eyes.
The window for Mars 2020 to actually Now, the anticipation is building.
launch in 2020 ran from July 17 through Who knows what discoveries await us all Jim Bell leads the Mastcam-Z camera team
August 15. If the mission missed that in Jezero, what new secrets about Mars on the Mars 2020 mission’s Perseverance
window, it would have had to wait until will be revealed by the images and other rover. He is an astronomer and planetary
September 2022. The challenges that the data the rover will collect. Everyone scientist at Arizona State University and
coronavirus presented made the efforts involved is extremely excited about what president of The Planetary Society.
of all involved — including at JPL, we will learn from the rover’s mission on
NASA’s Kennedy Space Center, United
Launch Alliance (the manufacturers of
the Atlas V rocket), and other NASA and
subcontractor facilities — to make the
launch window especially impressive.

The ambitious rover did go over its
original 2012 budget — but only by
around 12 percent, partly due to delays

WWW.ASTRONOMY.COM 31

SKY THIS MONTH Visible to the naked eye
Visible with binoculars
THE SOLAR SYSTEM’S CHANGING LANDSCAPE AS IT APPEARS IN EARTH’S SKY. Visible with a telescope
BY MARTIN RATCLIFFE AND ALISTER LING

FEBRUARY 2021 This month you’ll find
several planets hiding
Twilight planets delight in twilight. Careful
observers can even
follow Venus (pictured
here) and Jupiter into
daylight. JAMIE COOPER

Be ready to catch while. Mars dominates the eve- Morning triad
the early morning ning sky and enters Taurus this
appearance of four planets: month. Although distant from Altair
Mercury, Venus, Jupiter, and Earth and showing a tiny disk,
Saturn. They appear in the it will remain in our evening AQUILA
brightening morning twilight skies for a long while yet.
and some are challenging. Nunki Kaus
Jupiter passed Saturn last Attentive observers may SAGIT TARIUS Australis
December and now stands to catch Mercury February 1 in
its east. Both gas giants rise bright twilight after sunset. It’s CAPRICORNUS 10°
earlier each morning as they a challenging view now, follow-
increase their elongation from ing its greatest eastern elonga- Mercury Saturn
the Sun, preparing for a fine tion late last month. Begin your
spring lineup before dawn. attempt 30 minutes after sunset. Jupiter
Venus is heading to superior Can you spot the magnitude 0.9
conjunction with the Sun and planet 6° high in the western February 20, 30 minutes before sunrise
is briefly visible in the dawn sky? Watch with binoculars for Looking southeast
sky. Mercury is near the end of 15 to 20 minutes as the sky
its morning apparition. darkens and Mercury dips Early risers can catch Mercury forming the apex of a triangle with Saturn and
The evening skies of lower. The planet descends Jupiter shortly before sunrise on February 20. ALL ILLUSTRATIONS: ASTRONOMY: ROEN KELLY
February carry the distant quickly and 15 minutes before
giants Neptune and Uranus it’s gone, it stands 2° high — luck. Locations with the best a clear view to the west.
— Neptune is lost quickly in tough to spot at such a faint chance are those with fine Mercury passes through infe-
twilight, but Uranus lingers a magnitude, but some observers atmospheric transparency rior conjunction February 8
with clear skies may have good offered by a high altitude and and springs into the dawn sky

32 ASTRONOMY • FEBRUARY 2021

RISING MOON I Lunar strongmen

PROMINENTLY PAIRED CRATERS Atlas and Hercules and Atlas
Hercules rule the lunar northeast. Without com-
OBSERVING pare in strength, these mythological musclemen Mare
HIGHLIGHT have appropriately striking features named after Humboldtianum
them.
MERCURY, SATURN, and Atlas
JUPITER share the dawn sky Their chiseled forms seem to pop out on the
16th, lit by a rising Sun in the lunar sky. Atlas, the Hercules
this month. Catch them one closer to the limb, sports a rough floor and
February 20, forming a central peak. Just to the west, Hercules straddles N
triangle a mere 30 minutes the day-night line, the terminator. Over the next
few hours, watch the long shadows slowly E
before sunrise. retreat. The western inner walls face the
brilliant Sun, while their eastern sides The striking Atlas and Hercules craters
along with Jupiter — more on remain dark. Return on the 17th to see should draw your attention in mid- to
that later. the floor of Hercules — surprise! It's a late February. CONSOLIDATED LUNAR ATLAS/UA/LPL.
pool of frozen lava with the barest hint
Neptune makes a brief of a central peak and a sharp crater just INSET: NASA/GSFC/ASU
appearance early in February as off the bull’s-eye.
a binocular object in Aquarius. as it bobs up and down in its orbit around Earth,
It lies less than 20° high once Each bowl is surrounded by an apron of we see it from slightly different points of view.
the sky is dark. The magnitude debris. Under the low Sun angle, can you tell Astronomers call this apparent nodding motion
7.8 planet lies slightly less than which one drapes over the other? Researchers of our satellite libration.
2° northeast of Phi (ϕ) Aquarii, disagree over which formed first. It may help to
a dim 4th-magnitude star, on look with reversed lighting, when the setting Any time after First Quarter (the 19th), we’re
February 1. The pair’s angular Sun illuminates the craters’ eastern flanks on close to lunar high noon for both Atlas and
separation increases as the March 1, a few days after Full. Hercules. Without the shadows, Atlas practically
month progresses. By mid- disappears. In contrast, Hercules’s lava lake
month, the planet is too low to Luna slowly turns its nose up at us beginning stands out well against its neighboring light-
find, and it’s telescopically dis- on the 17th. Key in on the limb northeast of hued crater. Pay close attention — Luna reveals
appointing due to turbulence in Hercules and watch the dark floor of Mare a different face every night.
our atmosphere muddying the Humboldtianum shift out of sight from night to
view. It will reappear in the night. The Moon’s axis does not actually tilt — 3-6-1-6-6-7-5-1-3
morning sky later in the spring.
METEOR WATCH I A dim, dusty glow
Mars and Uranus begin the
month about 6.5° apart in the WITH NO MAJOR SHOWERS, False dusk
constellation Aries the Ram. February is traditionally a quiet
Uranus is only visible with bin-
oculars for most observers. At month for meteors. The average
magnitude 5.8, it may be visible
to the naked eye under excep- sporadic (random) rate for meteors
tionally clear sky conditions. It
lies 10.5° south of Hamal, the is seven per hour and there are occa-
brightest star in Aries. A wax-
ing crescent Moon lies within sional fireballs — meteors that break
5° of Uranus on February 17
and skips next door to sit 4° up and achieve a brilliance of Venus
south of Mars on the 18th.
or greater. These are, of course, rare,
Through a telescope, Uranus
displays a fine 3.5"-wide disk but worth spending time under a
with a greenish hue on nights
when stars are not twinkling night sky ready for their appearance.
badly — a sure sign of good
seeing conditions. The zodiacal light begins to make

Mars shines as a brilliant an appearance during moonless
beacon among the faint stars of
nights in February, March, and April.
— Continued on page 38
The evening view of this subtle

glow, which arises from the meteor-

itic dust that fills the plane of our

solar system, gets better as the Moonless February evenings are perfect for spotting the glow of the
ecliptic becomes more steeply zodiacal light from a dark location. BARRY BURGESS
inclined to the horizon. The first two

weeks of February are favorable, with the Moon in the morning sky. As soon as the Milky Way becomes

visible — arching from high up in Perseus through Orion and toward the southern horizon — look for a

faint, cone-shaped glow of light reaching up from the western horizon through Pisces, Aries, and into

Taurus at its narrowest. The zodiacal light is never seen from cities or towns, but is visible from country

locations with dark skies to the west.

WWW.ASTRONOMY.COM 33

N

STAR DOME

DRACO ι ζ δ α
η η

HOW TO USE THIS MAP NE M66 EPHEUS β γ

This map portrays the sky as seen ζ α ιβ
near 35° north latitude. Located η
inside the border are the cardinal URSA Polaris γ
directions and their intermediate MINOR α
points. To find stars, hold the map
overhead and orient it so one of Mizar NCP SIOPEIA
the labels matches the direction M51
you’re facing. The stars above B δ
the map’s horizon now match ε
what’s in the sky. C
E
The all-sky map shows
how the sky looks at: ROEMNAI N4GC α
ε C A M E L OPA R DA L I S
10 P.M. February 1 C α M82
9 P.M. February 15 M81
8 P.M. February 28 E γ MUARJ OS AR

Planets are shown S V αθ
at midmonth
CA
EN

β

ANTEISC β

NGP I
M64
ψ γβ ο

LEO MINOR λ δα
μ
ν β LYNX ι β
δ Capeαlla
η
ζε

MAP SYMBOLS β Denebola ε α CANCER Castor α M37 θ M36 M38 AURIGA
Pollux β ι
Open cluster E β θ η
Globular cluster ζ
Diffuse nebula VIRGO M65 β
Planetary nebula γ
Galaxy M44 ε M35
LEO
STAR
MAGNITUDES κ M1
αε
Sirius Regulus δζ μη ζ
0.0 3.0 α
1.0 4.0 G E λ γ ORIONλ Aldebaran
2.0 5.0 MI γ
N I ξ

ζ ε β Procyon π
C
ν α S E X TA N S HYDRA α β Betelgeuse α ε δ
MI AN ζ η
C R AT E R NO IS
δ R β

α α MONOCEROS M42
M47 Rigel
κ β

Sirius α μ

CANIS α β LEPUS

ρξ MAJOR M41 γβ

STAR COLORS ο2 ε

A star’s color depends α SE ANTLIA PYXIS η δ ζ
on its surface temperature. α σε
ψ VELA PUPPIS
The hottest stars shine blue Adhara

•• Slightly cooler stars appear white α
• Intermediate stars (like the Sun) glow yellow
• Lower-temperature stars appear orange π COLUMBA β CAE
• The coolest stars glow red ν
• Fainter stars can’t excite our eyes’ color ζ NGC 2477

receptors, so they appear white unless you σ
use optical aid to gather more light γ

S

BEGINNERS: WATCH A VIDEO ABOUT HOW TO READ A STAR CHART AT
www.Astronomy.com/starchart.

μ FEBRUARY 2021

ζ TA ER SUN. MON. TUES. WED. THURS. FRI. SAT.
β
δ C α NW 1 23456

A L 7 8 9 10 11 12 13

8 M31 E DA δ 14 15 16 17 18 19 20 ILLUSTRATIONS BY ASTRONOMY: ROEN KELLY
ANDROM PEGASUS α
86N9GC 21 22 23 24 25 26 27
δ β
28
η CA Note: Moon phases in the calendar vary in size due to the distance
αγ from Earth and are shown at 0h Universal Time.

β CALENDAR OF EVENTS
PERSEUS
γ 2 Asteroid Melpomene is at opposition, 2 A.M. EST
3 The Moon is at perigee (229,980 miles from Earth), 2:03 P.M. EST
M α 4 Last Quarter Moon occurs at 12:37 P.M. EST
M33 8 Mercury is in inferior conjunction, 9 A.M. EST
LU 9 Asteroid Pallas is in conjunction with the Sun, 3 P.M. EST
10 The Moon passes 3° south of Saturn, 6 A.M. EST
β
The Moon passes 3° south of Venus, 3 P.M. EST
ε U 11 Venus passes 0.4° south of Jupiter, 7 A.M. EST
Algol
ρβ G New Moon occurs at 2:06 P.M. EST
13 The Moon passes 4° south of Neptune, noon EST
N
Mercury passes 4° north of Jupiter, 2 P.M. EST
A 17 The Moon passes 3° south of Uranus, 11 A.M. EST
18 The Moon is at apogee (251,324 miles from Earth), 5:22 A.M. EST
I η
PISCES The Moon passes 4° south of Mars, 6 P.M. EST
R ARIES α 19 First Quarter Moon occurs at 1:47 P.M. EST
γβ 20 Mercury is stationary, 8 A.M. EST
T 21 Asteroid Amphitrite is at opposition, 11 P.M. EST
27 Full Moon occurs at 3:17 A.M. EST
ζ
η WWW.ASTRONOMY.COM 35

Pleiades
Path of the Sun (ecliptic) W

π Mars Uranus
δ
ε
S
3 α Mira ο α
HyadesELUM γ
αα CETUS
λ
TAU R U SHOROLOGIUM

ν

γ ERIDANUS

FORNAX

SW

PATHS OF THE PLANETS

UM

LAC LYR CVN LYN

CYG HER
OPH
SCO BOÖ COM Asteroid Amphitrite Irene GEM
CB reaches opposition
VUL February 21 CNC
DEL SER
PEG VIR LEO of the Sun (ecliptic)
SGE Eunomia
Path of the Moon Path

EQU Vesta CM
Celestial equator
AQL SER
SCT
AQR SEX Asteroid Melpomene
HYA reaches opposition
Sun Mercury Saturn February 1/2

CRV CRT

Jupiter Pluto

CAP LIB ANT CM
LUP Midnight
PA Venus PYX
GRU PUP
CA
MIC SGR

CEN

Moon phases Dawn

13 12 11 10 9 8 7 654 32 1
28 27 26 25 24 23
To locate the Moon in the sky, draw a line from the phase shown
for the day straight up to the curved blue line.

THE PLANETS Uranus THE PLANETS IN THE SKY
IN THEIR ORBITS
Jupiter Neptune These illustrations show the size, phase,
Arrows show the inner Saturn and orientation of each planet and the two
planets’ monthly motions brightest dwarf planets at 0h UT for the dates
and dots depict the in the data table at bottom. South is at the top
outer planets’ positions to match the view through a telescope.
at midmonth from high
above their orbits.

Venus Mars

Pluto Mercury

Ceres

Mercury Ceres PLANETS MERCURY VENUS
Inferior conjunction
Date Feb. 28 Feb. 1
is February 8 Magnitude 0.3 –3.9
Mars Angular size 8.0" 10.1"
Illumination 45% 98%
Earth Distance (AU) from Earth 1.652
Distance (AU) from Sun 0.843 0.728
Venus Right ascension (2000.0) 0.440 20h05.0m
Declination (2000.0) 21h01.6m –20°58'
Jupiter –16°12'

36 ASTRONOMY • FEBRUARY 2021

This map unfolds the entire night sky from sunset (at right) until sunrise (at left). Arrows FEBRUARY 2021

JULY 2021and colored dots show motions and locations of solar system objects during the month.

CAS

PER AND LAC Callisto 1
2
AUR CYG Europa 3
ORI 4
TRI Io 5 Ganymede
6 Callisto
Mars ARI PEG Ganymede 7 Jupiter
8 Io
Uranus DEL JUPITER’S 9 Europa
PSC EQU MOONS 10
11
TAU Dots display 12
positions of 13
Neptune Galilean satellites 14
at 6 A.M. EST on 15
CET Sun AQR the date shown. 16
South is at the 17
Ceres top to match the 18
view through a 19
LEP ERI FOR SCL CAP telescope. 20
COL CAE PA 21
22
GRU MIC 23
24
Early evening 25
26
22 21 20 19 18 17 16 15 14 13 12 11 27
28
Jupiter S
WE
Saturn
N

10"

Uranus Neptune Pluto

MARS CERES JUPITER SATURN URANUS NEPTUNE PLUTO

Feb. 15 Feb. 15 Feb. 28 Feb. 28 Feb. 15 Feb. 15 Feb. 15
0.7 9.3 –2.0 0.6 5.8 7.8 15.1
7.0" 0.4" 33.0" 15.4" 3.5" 2.2" 0.1"
89% 99% 100% 100% 100% 100%
1.329 3.732 5.972 10.811 100%
1.567 2.941 5.076 9.978 20.072 30.831 35.065
19.766 29.926 34.221
3h08.4m 0h03.1m 21h14.9m 20h42.5m 2h18.7m 23h22.9m 19h50.3m
19°03' –8°21' –16°34' –18°41' 13°24' –5°09' –22°18'

WHEN TO

SKY THIS MONTH — Continued from page 33 VIEW THE

PLANETS

week of the month, but the

tiny disk makes them hard to EVENING SKY

spot except under optimum Mars (southwest)
seeing conditions. Skilled Uranus (southwest)
observers who practiced video
Neptune (west)

capture during last year’s MIDNIGHT

opposition can still bring them Mars (west)

out if conditions cooperate. MORNING SKY
Four planets congregate in
Mercury (east)
the dawn twilight this month. Venus (east)
Some events are difficult to Jupiter (east)
catch due to their proximity Saturn (east)

to the Sun. For example, on

February 6, Venus stands less

Although no meteor showers take place in February, keep your eyes on the sky than a Moon’s-width southeast
of Saturn, but they rise only Venus, on its way to a late
for sporadic meteors, including the occasional fireball. MIKE LEWINSKI

half an hour before the Sun. March superior conjunction,

Aries, beginning the month at most observers in the U.S. Even at magnitude –3.9, Venus passes 26' due south of Jupiter

magnitude 0.5 and dipping to The lack of albedo features is will be hard to see. Saturn is February 11. They’re located just

0.9 by the end of February. The apparent during mid-February, not visible at a much dimmer 10.5° east of the Sun. Jupiter

Red Planet this month has as desert regions transit the magnitude of 0.6. shines at magnitude –2; the pair

competition from Aldebaran, martian disk during our eve-

the brightest star in Taurus the

0.3Bull, which glows at magnitude

0.8. Can you tell which night
nings. Solis Lacus and Sinus Between February 1 and 28, Mars retreats
Meridiani, two distinctive dark nearly 0.3 AU from Earth.
features, are on view in the last

they are both equal brightness?

Mars moves into Taurus COMET SEARCH I Challenge versus chance
February 23 and ends the
month nearly 14° northwest of

Aldebaran and nicely placed COMET ENTHUSIASTS are used to excitement, disappointment, and satisfaction all in one month. No
about 3° southwest of the con- one can be sure which it will be this spring. As Earth circles the inner solar system, some comets coin-
trasting blue stars of the cidentally arc behind the Sun, popping into visibility with only three months’ notice before they peak,
Pleiades (M45). missing our publication deadline.

The Red Planet presents a Surprising us twice since its discovery, 17P/Holmes has outburst to 2nd magnitude. Cruising in front of

tiny disk through telescopes as the circlet of Pisces, will it shine anew? Meanwhile, as 141P/Machholz 2 sails from Cetus to Orion, its last

its distance from Earth contin- fragment might flare up to

ues to increase apace. Its 10th magnitude for a final show. Comet 88P/Howell
gibbous phase is a distinctive With great but not absolute

90 percent lit. On February 1, confidence, we expect Comet δ N ιθ
it’s already 1.2 astronomical 88P/Howell to present a challenge ε
units from Earth (1 astronomi- for an 8-inch scope under a dark
cal unit, or AU, is the average sky. Once you’ve confirmed the PISCES λ γ
Earth-Sun distance). That dis- starfield is right, pump up the
tance increases to nearly magnification to about 200x. Get Mar 2 Path of
1.5 AU by February 28. The comfortable, dark adapt as much 25 Comet Howell
disk’s angular size shrinks as possible, and patiently scan for
from nearly 8" to 6.4" over the a very small fuzz — picture a E 20
course of the month. 13th-magnitude elliptical galaxy. CETUS
Tapping the scope gently can
Features so familiar during leverage our eyes’ low-light 15
Mars’ opposition late last year motion-detector system, while
are now tougher to spot. also suppressing “phantom 10
During the first five days of galaxies” produced by a noisy
February, the darkest — visual cortex. NGC 157 5 φ
Syrtis Major — swings into ι ψ1
view in the evening between The best comet hunting this Feb 1
sunset and local midnight for month is during the moonless first AQUARIUS Neptune
half of February.
η 2°

A challenging 88P/Howell skims through Pisces on its way from Aquarius to
Cetus this month. The location of Neptune is shown on February 7. Should
they flare up, 17P/Holmes is west of this field and 141P/Machholz 2 is east.

38 ASTRONOMY

LOCATING ASTEROIDS I

Buzzing the Crab

Bull crossing IT’S TWO-FOR-ONE asteroids this month. Floating only one
field apart, 18 Melpomene and 60 Echo track across southern
Betelgeuse Aldebaran Pleiades Cancer. The celestial crab is well placed one-third of the way up
ORION the eastern sky once darkness sets in. This aquatic constellation
boasts the splashy Beehive Cluster (M44); start with this show-
Sirius Mars piece, then shift a few degrees south to Alpha (α) Cancri and M67.
TAU R U S
CANIS From the 5th to the 8th, magnitude 10 Echo shares the
MAJOR Hamal medium-power field with the well-studied cluster M67.
ARIES Melpomene is just over 1° to the north and is a bit brighter at
Rigel magnitude 9.5. Crank the power to the max on M67 and test your
limiting magnitude against the chart in the Royal Astronomy
LEPUS Menkar Uranus Society of Canada’s Observer's Handbook or one generated online
at the American Association of Variable Star Observers’ website,
ERIDANUS www.aavso.org.

CETUS Until much brighter 4 Vesta arrives in spring, we must be
meticulous in our identification of these main-belt asteroids.
10° Starhop carefully, sketch a field in the expected area, then come
back a night or two later to see which dot has moved. The orange
February 28, 8 P.M. star FX Cancri varies only slightly from magnitude 6.7, making a
Looking southwest nice reference in the same field.

Mars crosses into Taurus February 23 and ends the month beneath the Thanks to the longer nights of February, you might be able to
Pleiades (M45). Uranus floats nearby in Aries and is visible with binoculars see these small worlds move slightly over a four-hour session.
or a telescope.
Double feature

may be seen in binoculars planets’ visibility improves ξ γN
20 minutes or so before sunrise, each consecutive morning.
but will be very challenging. M44
Observers, be very cautious — Try on the morning of
you can easily lose track of time Saturday, February 20, to spot δ ζ2
as the Sun comes up. Protect all three planets in a triangle:
yourself by setting an alarm to Saturn and Mercury rise CANCER Tarf
go off several minutes before together 4.4° apart around 2°
sunrise. Never scan the skies 5:40 A.M. local time, followed Mar 2
after sunrise, because an acci- by Jupiter 7° east of Saturn E 25
dental view of the Sun through about 22 minutes later. 20
binoculars will cause lasting π Path of
damage to your eyes! Mercury and Saturn match Melpomene 15
in magnitude February 22, 10 Mar 2
Observers with clear, trans- when they stand almost 5° high 5 FX 25
parent daytime skies and an 40 minutes before sunrise. Fαeb 1 20
accurately aligned telescope Jupiter stands less than 1° high, M67
on February 11 can use their but its brilliance makes it more 10 15
go-to device to find Venus and easily visible. It lies about κ Feb 1 5 Path of Echo
Jupiter in daylight. 5° east (lower left) of Mercury,
while Saturn stands 4° to Asteroids Melpomene and Echo travel together this month through
On February 15, Saturn Mercury’s southwest (right). Cancer. Close by is the sparkling Beehive Cluster (M44).
and Mercury rise together in
the eastern sky, but remain The triangle formed by — all three planets are cur- Saturn are full. Jupiter spans
difficult objects due to their this trio of planets flattens as rently on the far side of the 33" and is accompanied by its
relative faintness in twilight. Mercury drops in declination Sun. Mercury is closest to four Galilean moons, just vis-
By February 18, they stand in late February, brightening as Earth at 0.85 AU, while Jupiter ible in the shimmering haze.
roughly 3° high 45 minutes it does so. On February 28, it is at 6 AU and Saturn is a dis- Saturn’s disk is 15" wide and its
before sunrise. Mercury has shines at magnitude 0.3 and tant 10.8 AU away. bright ring system spans 34" at
brightened to magnitude 1.2, stands only 3° west of Jupiter, its widest.
while Saturn remains easier with Saturn 5.5° to Mercury’s If you’re able to swing a
at magnitude 0.6. The two west. It’s amazing to get this telescope towards these plan- Martin Ratcliffe is a
view across the solar system ets, you’re in for a visual — planetarium professional and
though short-lived — treat, enjoys observing from Wichita,
GET DAILY UPDATES ON YOUR NIGHT SKY AT since twilight is advancing Kansas. Alister Ling, who
www.Astronomy.com/skythisweek. quickly. Mercury displays a lives in Edmonton, Alberta, is a
46-percent-lit disk spanning longtime watcher of the skies.
8", whereas both Jupiter and

WWW.ASTRONOMY.COM 39

Corona
light

Missed last year’s annular eclipse?
We’ve got you covered with some of the best shots out there.

BY JAY PASACHOFF

BACKGROUND: The Mango
Education Group experienced
annularity during clear weather
from Dehradun, which is the
most populous city in the Indian
state of Uttarakhand. That
fortunate weather allowed them
to capture this crisp shot of the
thin circle created by the Sun’s
disk stretching out just beyond
the Moon’s silhouette. HARINDRA

BARAIYA (WILDLIFE INSTITUTE OF INDIA/MANGO
ASTRONOMY CLUB); IMAGE FORWARDED BY STEPHEN
INBANATHAN (AMERICAN COLLEGE IN MADURAI)

RIGHT: On June 21, the Moon was
relatively far from Earth thanks to
its slightly elliptical orbit. That
meant its angular size was
smaller than usual. Therefore, it
couldn’t fully block the solar disk
when the Sun, Moon, and Earth
aligned, or entered syzygy, as
shown in this artist’s illustration.

ASTRONOMY: ROEN KELLY AFTER ERNEST T. WRIGHT
(NASA’S SCIENTIFIC VISUALIZATION STUDIO)

40 ASTRONOMY

he wild year of 2020 otherwise. And although I don’t keep in
boasted two solar eclipses: constant contact with every one of them,
an annular eclipse on when an eclipse passes overhead anywhere in
June 21 and a total solar the world, I have a good chance of hearing
eclipse on December 14. from some of my old friends who are eager
to share their new pictures.
TTravel restrictions pre-
vented North Americans, At the time of this writing, the next solar
as well as many others in the Western eclipse to be seen from Earth will be total,
Hemisphere, from viewing the path of annu- with its peak occurring near the border of
larity that stretched from Africa through the Argentina and Chile on December 14, 2020.
Middle East to Pakistan, India, mainland Be sure to keep an eye out for images of
China, and Taiwan. Fortunately, local eclipse December’s total solar eclipse in future issues
viewers who managed to get beneath the of Astronomy.
Moon’s shadow captured wonderful images
of the breathtaking event. Meanwhile, the next annular eclipse will
be on June 10, 2021. Its path will trek from
The following is a smattering of shots southern Canada over the North Pole and
from last June’s annular eclipse, which I down to the Russian Far East. Observers in
monitored into the wee hours of the morn- the northeastern United States will be happy
ing with the help of email, the web, and to learn that partial phases of this annular
livestreams from the Middle East and Asia. eclipse will be visible to them in the early
My decades-long interest in eclipses, and the morning. So, make sure to get your filtered
resulting expeditions I have taken to view solar eclipse glasses now, available at
them, have allowed me to meet many fasci- MyScienceShop.com.
nating people whom I never would have
And don’t forget: Share what you see!

A RINGED ECLIPSE

The word annular comes from annulus, which means “ring.” So, when the Moon is just far
enough away from Earth that it leaves the outer perimeter of the Sun’s disk unobscured, the
result is often referred to as a “ring-of-fire” eclipse. At maximum coverage, this outer band of
sunlight is up to a few percent of the solar disk’s diameter. So, technically, it could be called
a “ring-of-photosphere” or a “ring-of-sunlight” eclipse.

The term “ring-of-fire” has murky origins dating back at least 150 years, but its modern
usage in reference to annular eclipses has been around for at least a few decades, when it
started popping up in various publications. However, “ring-of-fire” is somewhat misleading ter-
minology, and it is disliked by many professional and amateur astronomers, or so-called
umbraphiles (the umbra is the dark part of a shadow). Contrary to common conception, there
is no chemical fire on the Sun. Rather, we owe the warmth and light we receive from the Sun
to the clean thermonuclear fusion of hydrogen gas safely occurring some 93 million miles
(150 million kilometers) away.

IMAGES: JAY PASACHOFF. COMPOSITE: MUZHOU LU

WWW.ASTRONOMY.COM 41

1
2

3

1 The Moon’s shadow AN UNFILTERED VIEW LEADS TO A REVISION
first touched the Republic of
Congo during the June 21 annular The June 21 annular address to remember: eclipses.info. The working
eclipse. After it departed Africa, it eclipse also group also serves as a clearinghouse for profes-
went through the Middle East, then traced a path sionals pursuing international eclipse expeditions,
passed through southern Pakistan, through coordinating such matters as visas, customs, and
northern India, mainland China, and Pakistan, where the shipping of equipment.
Taiwan before vanishing southeast the cloud-cover
of Guam. The annular eclipse path, forecast was For these images, Zia and Kentrianakis forwent
which stretched 9,058 miles (14,578 not as favorable filters in order to capture detailed views of Baily’s
km), was just 13 miles (21 km) wide as in the lower beads, which occur when sunlight peeks through
and maximum eclipse (99 percent) Arabian Peninsula. valleys along the lunar limb. This allowed them to
lasted only 38 seconds. MICHAEL ZEILER successfully detect the solar chromosphere, and
Fortunately, it turned even the inner solar corona.
2The path of annularity also out to be very clear.
grazed Saudi Arabia, resulting From Sukkur — a city in Prior imaging of Baily’s beads taken during pre-
in a partial eclipse for many. the Pakistani province of Sindh — Talha Moon Zia, vious total solar eclipses led to discussions
Abouazza Elhamdi of the Astronomy who is a research astronomer at Pakistan’s between me, Xavier Jubier, and Ernest T. Wright of
and Physics Department of King National Center for Big Data and Cloud Computing/ NASA’s Scientific Visualization Studio. We con-
Saud University captured this NED University of Engineering & Technology, cluded that the IAU’s nominal solar diameter — the
sequence of partial phases in the obtained these wonderful unfiltered views of the defined size of the Sun’s photosphere, which is
early morning from Riyadh. I am annular eclipse. The shots were created by stacking used for predicting the length of eclipse totalities
working with Abouazza, Marcos several short-exposure images and were taken down to a fraction of a second — needed a minor
Peñaloza-Murillo of Venezuela, and under the guidance of Michael Kentrianakis, the revision. By comparing our observations to simula-
Michael Roman of England to former project manager of the American tions by Jubier of the expected Baily’s beads for this
analyze how eclipse darkening Astronomical Society’s 2017 U.S. eclipse efforts and eclipse, which were based on high-resolution 3D
impacts the local temperature a member of our International mapping of the lunar surface obtained by NASA’s
and humidity in desert climates. Astronomical Union’s (IAU) Working
Group on Solar Eclipses. Lunar Reconnaissance Orbiter and the
ABOUAZZA ELMHAMDI Our IAU group focuses on being Japanese Kaguya mission, we found
a central resource for anyone our suspicions were confirmed.
3LEFT: Unlike central Saudi looking to find out more about Zia’s observations, as well as
Arabia, observers in Izki, Oman, past or upcoming solar eclipses. Jubier’s simulations, show the
did see annularity. Alaa Ibrahim and To do this, we maintain a web- true size of the Sun’s photo-
Zach Ioannou of the Astronomy site at the easiest possible sphere is slightly larger than
Group in the Department of Physics previously thought.
at Sultan Qaboos University
captured a series of images with BOTH IMAGES: NCBC-NEDUET
the aid of a hydrogen-alpha filter,
including this single short exposure.
RIGHT: Made by stacking 210
images, this view reveals solar
prominences, or bright tendrils of
chromospheric-temperature plasma
that extend into the corona. During
the event, the observers tracked
changes in ambient temperature
and humidity. Before the eclipse,
it was 113 degrees Fahrenheit
(45 degrees Celsius), which caused
some equipment to overheat. But as
the Moon blotted out most of the
Sun’s disk, the temperature dropped
down to 90 F (32 C). LEFT: A.I. IBRAHIM.

RIGHT: A.I. IBRAHIM/I.A. ALSHAIKH

4 5
7
4 Rafay Kazmi, a student
at Williams College in
Williamstown, Massachusetts,
observed a partial eclipse from his
home in Islamabad, Pakistan. Here,
he and his sister are seen viewing
the eclipse through special solar
filters, one of thousands left over
from the 2017 Great American
Eclipse and available through
Astronomers Without Borders.

RAFAY KAZMI

5Clouds only served to add
mystique to this view of the
eclipse from the city of Sirsa in the
northern Indian state of Haryana,
taken by Neelam and Ajay Talwar.

NEELAM & AJAY TALWAR

6 This series of images, showing
the partial eclipse as seen from
Coimbatore, a city in the south
Indian state of Tamil Nadu, was
captured by members of the Mango
Astronomy Club. OBULI CHANDRAN

7The Talwar team also captured
this series of images tracking
the progress of the annular eclipse
over Sirsa. Even through the
clouds, one can identify Baily’s
beads, the solar chromosphere,
and, perhaps, even the solar
corona. NEELAM & AJAY TALWAR

6

WWW.ASTRONOMY.COM 43

8 ECLIPSE RESOURCES

9 Many observers who were unable to personally see
the annular eclipse dim the skies during the daytime
8 Amateur astronomer Zhou instead opted to monitor images and livestreams of the
Guanhuai (left), with whom I event aired during the middle of their local night — an
have previously corresponded option not available to eclipse enthusiasts just a few
about earlier eclipses, sent an decades ago.
image of the partial eclipse (right)
as seen from Jinan, Shandong Now, worldwide communication and online eclipse-
province, China. Here, the partial mapping tools, like those from Xavier Jubier of France
eclipse reached its greatest (http://xjubier.free.fr/ase2020map) and retired astro-
coverage at 15:55 local time with physicist Fred Espenak (EclipseWise.com), provide
67 percent of the Sun’s disk detailed eclipse data for any location on Earth.
blocked. ZHOU GUANHUAI Additionally, cartographer Michael Zeiler of New
Mexico has meticulously created high-quality eclipse
9 Due to travel restrictions maps, while cloudiness statistics over the decades
related to the COVID-19 have been gleaned and put into context by Jay
pandemic, I was unable to venture Anderson of Canada. (Anderson and I jointly authored
to Europe. This image, however, the Peterson Field Guide to Weather, which is being
came from Thessoliniki, Greece. published in summer 2021.)
It was captured by Aris Voulgaris,
with whom I closely work on total All of these resources are linked on the website for
solar eclipses. ARIS VOULGARIS the International Astronomical Union’s Working Group
on Solar Eclipses (http://eclipses.info), which I chair.
10Near the end of the path Additionally, observations of the 75 or so solar eclipses
of annularity in Guam, the I worked on in the past are posted to the Williams
eclipse was visible with 97 percent College Eclipse Expeditions website (https://sites.
coverage, as seen in this eerie shot. williams.edu/eclipse).
The path of annularity continued
about 50 miles (80 km) out to sea — 10
briefly tempting me to fly to the U.S.
territory for a quarantined glimpse
from a boat. DEAN PATRICK SERVITO

44 ASTRONOMY • FEBRUARY 2021

11

1 1 A camera mounted to the
outside of the International
Space Station captured this shot
of the Moon’s shadow racing
across Earth (near the border of
Kazakhstan and China) during
the June 21 annular eclipse. In
the foreground, a Japanese
cargo spacecraft is visible.

NASA/ISS EXPEDITION 63

12 The X-ray telescope on
the Japanese Hinode
spacecraft captured this series of

shots, which have been rescaled

and colored, showing the Moon

blocking the Sun’s disk during the

12 June eclipse. Astronomer Taro

Sakao of the Japan Aerospace

Exploration Agency (JAXA) took

13 advantage of Hinode’s vantage

point to observe how plasma

moves within the high-speed

solar wind stream, using the lunar

Jay Pasachoff is Field silhouette for calibration of stray
Memorial Professor of light. JAXA/HINODE (THANKS TO ALPHONSE

STERLING OF NASA’S MARSHALL SPACE FLIGHT

Astronomy at Williams CENTER, AND KATHY REEVES AND LUCAS GULIANO
College in Williamstown, OF THE HARVARD-SMITHSONIAN CENTER FOR
ASTROPHYSICS)

Massachusetts, and 13 The passage of the Moon’s
chair of the International shadow across Earth’s
Astronomical Union’s surface was also tracked by the
Working Group on Solar European Meteosat-8 and the
Eclipses. He has worked Japanese Himawari-8 spacecraft.
on 75 solar eclipses and Here we see a Meteosat view of
written about the Sun for Moon’s shadow over northeast
Astronomy since its very Africa, the Red Sea, and the
first issue. His research is Arabian Peninsula. The next
annular solar eclipse will occur
June 10, 2021. EUMETSAT

sponsored by the NSF.

WWW.ASTRONOMY.COM 45

With three Messier objects and loads of other bright targets,
the Charioteer has a lot to offer. // BY MICHAEL E. BAKICH

The constellation N
Auriga (pronounced NGC 2126
or-EYE-guh) the
Charioteer, a star AURIGA Capella NGC 1664
pattern known by this name α
for several thousand years, is β
easy to recognize primarily ε
because of its brightest star,
Capella (Alpha [α] Aurigae). NGC 2281 ρ ηζ
This luminary is the sixth- E
brightest nighttime star and λ
shines with an intense yel-
low light. The constellation’s ντ NGC 1857 μ ω
Beta star, magnitude 1.9
Menkalinan, is 40th brightest. θυ σ
NGC 1778
The Charioteer is visible
in the evening from mid- M38
autumn through winter in NGC 1907
the Northern Hemisphere.
Its center lies at R.A. 6h01m NGC 1931 IC 405 ι
and Dec. 42° north. Auriga
ranks 21st in size out of the M37 M36 IC 410
88 constellations, covering χ NGC 1893
657.44 square degrees Barnard 29
(1.59 percent) of the sky. Its
size is a bit of a hindrance to 5° κ 26
its visibility, however. It lies in β
the middle of the constella- midnight. With respect to
tion ladder (43rd) in terms of visibility, anyone living north ASTRONOMY: RICHARD TALCOTT AND ROEN KELLY
overall brightness. of latitude 34° south can see
the entire figure at some time Auriga contains three its borders for you to point a
The best date each year to during the year. And it’s com- Messier objects (all open clus- telescope at. Good luck!
see Auriga is December 21, pletely invisible only to those ters) and several other open
when it stands opposite the who live at latitudes south of clusters and emission nebulae. Michael E. Bakich is a
Sun in the sky and reaches 62° south. Because it lies along the Milky contributing editor of Astronomy
its highest point at local Way, it doesn’t contain any who enjoys slowly moving his
galaxies. As you can see, how- telescope through a single
ever, lots of targets lie within constellation.

1 Open cluster NGC 2 NGC 1664 is an
2281 glows at attractive open
magnitude 5.4 and cluster 2° west of
measures 14' across. magnitude 3.0 Epsilon
It lies 0.8° south-
southwest of magnitude (ε) Aurigae. It glows at
magnitude 7.6 and
5.0 Psi⁷ (ψ⁷) Aurigae. spans 18'. A 4-inch
Through a 4-inch scope scope at 100x reveals
at 100x, you’ll spot two three dozen stars. The
dozen stars. Four stars background star field is
forming a parallelogram rich, but you’ll have no
sit at the center of the trouble picking out the
cluster. ANTHONY AYIOMAMITIS cluster. JASPAL CHADHA

46 ASTRONOMY • FEBRUARY 2021

3 NGC 1778 is a magnitude 7.7 open 4 Barnard 29 is a dark nebula that 5 The Flaming Star Nebula (IC 405) appears as a dim 30' by 20' wisp of light.
cluster with a diameter of 8'. You’ll lies 2.4° southeast of magnitude To observe it, first find AE Aurigae, which lies 4.2° east-northeast of Iota.
find it 2° east-southeast of magnitude Through a 6-inch scope, the nebula appears triangular. ALISTAIR SYMON
2.7 Iota (ι) Aurigae. Through a 12-inch
5.1 Omega (ω) Aurigae. Through a scope, B29 appears as a gray, mottled
4-inch scope, you’ll see two dozen region that blends gradually into its
stars unevenly spread across this starry surroundings. The darkest area
cluster’s face. Double the aperture appears 15' across. MARTIN C. GERMANO
to 8 inches, and you’ll raise that star
count to 50. MARTIN C. GERMANO

6 Open cluster NGC 1857 sits 0.8° 7 IC 410 is a large (40' by 30') emis- 8 NGC 1907 is a magnitude 8.2 open 9 The Starfish Cluster (M38) is
south-southeast of magnitude 4.7 sion nebula 2.4° west-northwest cluster that spans 6'. A 4-inch the westernmost and faintest
scope at 100x shows about a dozen (magnitude 6.4) of the three Messier
Lambda (λ) Aurigae. It glows at mag- of magnitude 4.7 Chi (χ) Aurigae. The stars. Use a low-power eyepiece and open clusters in this constellation.
nitude 7.0 and measures 5'. Through nebulosity glows brightest in an area you’ll sweep up an even-brighter open A 4-inch scope will reveal three
an 8-inch scope, you’ll see 25 stars 5' in diameter on the northwestern cluster: M38, 0.5° to the north- dozen stars in an area 20' across.
around 13th magnitude. The exception edge. Use a 12-inch scope with an northeast. MARTIN C. GERMANO
is SAO 57903, a magnitude 7.4 yellow Oxygen-III filter and this object will ANTHONY AYIOMAMITIS
star at the center. MARTIN C. GERMANO knock your socks off. MARK HANSON

10 Emission nebula NGC 1931 11 The Pinwheel Cluster (M36) is 12 The Salt and Pepper Cluster 13 NGC 2126 lies midway between
sits 0.8° east-southeast of the least spectacular of the (M37) displays an even magnitude 1.9 Menkalinan (Beta
magnitude 5.1 Phi (ϕ) Aurigae. An Messier trio in Auriga. At magnitude distribution of stars — a rarity in open [β] Aurigae) and magnitude 3.7 Delta
8-inch scope at 200x shows the 6.0, however, it still outshines 99.99 clusters. A 3-inch scope reveals 50 (δ) Aurigae. It glows at magnitude
nebula, which spans 4'. It orients percent of the sky’s star clusters. stars. Through a 10-inch scope, you’ll 10.2 and spans 6'. Through a 6-inch
northeast to southwest and shows Through a 4-inch scope, you’ll see count 200, and a 16-inch will reveal telescope, you’ll see about 20 stars.
non-uniform brightness across its several dozen stars strewn across an 500. M37 glows at magnitude 5.6 and The magnitude 6.0 star SAO 40801
face. AL AND ANDY FERAYOMI/ADAM BLOCK/NOAO/ area 12' wide. ANTHONY AYIOMAMITIS is 20' across. ANTHONY AYIOMAMITIS lies 3' northeast of the cluster.

AURA/NSF MARTIN C. GERMANO

WWW.ASTRONOMY.COM 47

These computer-generated images
from the Copernicus Complexio
cosmological simulation show stellar
halos of Milky Way-like galaxies. The
visible streams result from tidally
disrupted satellite galaxies. A.P. COOPER

(NATIONAL TSING HUA UNIVERSITY, TAIWAN)/W. HELLWING

AND THE VIRGO CONSORTIUM

This discovery image of a giant,
low-surface-brightness, looplike stellar
structure around edge-on spiral
NGC 4013 was obtained with a 20-inch
amateur telescope. The marked redder
color of the stream material compared to
the outer parts of the disk suggests that
this loop did not originate from the disk
itself, but rather is the tidal stream of a
dwarf galaxy being destroyed by its
interaction with NGC 4013. R. JAY GABANY

48 ASTRONOMY

STUDYING
GALAXIES

with amateur images

Advances in our understanding of galaxy formation aren’t just
coming from large, professional telescopes.

BY DAVID MARTÍNEZ-DELGADO AND R. JAY GABANY

FFROM THE TIME amateur astronomers
Galileo first peered into his equipped with modest
telescope until the middle instruments as well. One
of the 19th century, profes- such amateur was sanitary
sional telescopes required engineer Andrew Common.
the observer to look In 1883, he took the first
through an eyepiece. As a photograph of faint struc-

result, astronomers manu- tures in the Orion Nebula

ally logged mountains of (M42) that were not visible

information and telescopic through an eyepiece.

drawings in journals. Others, photographing a

Then came photography. plethora of objects, quickly

Almost from its inception, followed.

photography offered the

tantalizing prospect of serv- Paving the way

ing as a tool to discover and As the 21st century

document new, hitherto- dawned, the digital imag-

unseen phenomena. In fact, ing technology that had

by the beginning of the already replaced chemical

20th century, advancements photography at professional

in photography enabled observatories began to

career astronomers to lay trickle down into consumer

down their pencils and products. This enabled

trade their telescope amateur astronomers to

eyepieces for glass plates purchase, at a reasonable

coated with photographic cost, computer-controlled

emulsions. charge-coupled device

In addition to appealing (CCD) cameras expressly Dwarf galaxy Donatiello I was captured through a Takahashi FSQ-106 refractor
to professional astronomers, designed for use with small at f/3.6 and a commercial CCD camera at the Avalon Merlino, the personal remote
this potential captured the telescopes. At the same observatory of Avalon Instruments. The total exposure time was 24,300 seconds
imagination of resourceful time, motorized mounts through a luminance filter. The zoomed-in panel shows a red-filtered image of
Donatiello I from the 10.4-meter Gran Telescopio Canarias in La Palma, Spain. G. DONATIELLO

WWW.ASTRONOMY.COM 49

This wide-field mosaic of the driven by electronic maps of
Magellanic Clouds was taken through the sky enabled amateurs to
a Canon EF 50mm f/1.4 USM prime place any celestial object at
lens from La Silla Observatory, Chile. the center of an electronic
imaging chip and track it
YURI BELETSKY with high precision.

The Small Magellanic Cloud As a result, modest equip-
shows a lot of detail through a Canon ment became a tool for
EF 200mm f/2.8L lens from Hacienda obtaining ultra-deep images
Las Condes, Chile. A faint, shell-like that could capture the
structure composed of young stars is outskirts of nearby massive
visible on the northeast side (upper galaxies and survey vast areas
left in this image) of the galaxy. of the sky with unprecedented
depth. This enabled a new
YURI BELETSKY/FABIAN NEYER/BERNHARD HUBL type of collaboration between
world-class amateur astroim-
50 ASTRONOMY • FEBRUARY 2021 agers and international teams
of professional astronomers
exploring one of the funda-
mental questions in modern
astrophysics: How did massive
galaxies like our Milky Way
come to be?

The standard model of the
universe’s formation predicts
that the elegant galactic spirals
we see today, including our
own Milky Way, arose hierar-
chically. They did this by
capturing much smaller gal-
axies, some only composed of
dark matter. State-of-the-art
computer models indicate the
Local Group and its neighbors
should still contain evidence
of this ancient galactic
cannibalism.

During the last decade,
amateur telescopes have
revealed, in many cases for the
first time, an assortment of
large-scale tidal structures
around nearby massive galax-
ies. They also have imaged
formerly unknown nearby
low-surface-brightness star
systems. And amateurs using
telephoto lenses have traced
interactions between the
Magellanic Clouds and other
Milky Way satellite galaxies.
All of these amazing images
have provided evidence to
support our understanding of
galactic evolution as predicted
by current simulations.