SOLAR SYSTEM

NOR~Z\L~ \ lorntJeirful Wo~ldJ of



SCIENf:E







.
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LI&















































Solar System

Giant gas planet





.S) Jupiter iS the 0 on Juprter, or any crther gas
,'\stronauts will never land
giant, l,ecause there Is no
Solar System's bi99est solid surl'ace to touch down on.
0
planet. It is 11 times the
size of Earth. Jupiter, along

with Saturn, Uranus and
Neptune, are known as gas
giants, because they are
huge planets made of gas
and liquid.




S S Jupiter ic; made mainly
or hydrogen and helium. Below its
atmosphere, gas is compressed
(squashed) so much that it changes
to liquid. Deeper still it is compressed
even more, causing the liquid to
behave like metal. As Jupiter spins,
this liquid metal creates a magnetic
field, which is the strongest in the
Solar System. At the centre there is
thought to be a small, rocky core.













Jupiter has a dense
core about the size
l:at'th, surrounded by
lictuid and gas.

A a ter• Th .
oltnan 90ds . e king oft
a,r,eter• 1,;2
9
p 1.2 titne~ E , B,; kilometres
Dist arth)
. ance fro,r, h
tnetr, t e Sun: ·;?9 million
e to
e to orb~tonce: 9.9 hours
, the Sun• 11
e te · .9 years
. 10°








S' It takes less than
ten hours tor Jupiter to spin
Te1nj>et'®Jre<3 at the tops ot the
clouds are around -\\0°C, but the once. This is faster than any
te1nj>el'Cffilre increases deeper in other planet in the Solar System,
the atmosphere
and even causes Jupiter to bulge
in the middle.




S 'I The Great Red
Spot is a per!Ylanent stor!Yl
in Jupiter's atmosphere. It is
a vast hurricane, much larger
than Earth. The storm has been
raging for hundreds of years.




r I DON'T BELIEVE IT!
Jupiter is mode en the sotne
\ moterio\ os o stor, so i~ it _hod
corried on growing ond go1ned
enough !YIOSS, it could
h<Ne \,ecO!Yle the
So\dr s~IYl's
second star.






'l-9

Jupiter's moons






s a Ju1>iter has more moons than

any other- ~lanet. This is because of its
huge size, as it means it has a very strong
pull of gravity. So far, 67 moons have
been discovered. The four biggest can be
:,I
seen with binoculars. They're known as the
Jt. Through a pair ol' binoculars,
Galilean moons, because they were seen for Jupiter's Galilean moons look like a
line ol' stars alongside the planet.
' the first time by the Italian astronomer,

Galileo Galilei, in 1610.




S 9 The Galilean moons were a You will need:
surprise ror astronomers. These icy a pair of binoculars
worlds all have very different features, and ~/ear night, find the brightest
are not the dead, dusty worlds that _m the sky. Look at it through
scientists expected them to be. no~ulars. If it has a line of tiny
th hst ol' Jupiter's moons to be t on one or both sides
'f The Galilean moons were e d rbiting another planet. und Jupiter - and i '
hst moons ,oun °
discovered, an d th e 1





,o Jupiter's
largest moon, Ganymede,
is also the bi99est in
the Solar System. It is
1.5 times the size of our
Moon. Ganymede is
covered with a deep layer
of ice. The second largest,
Callisto, is the most
heavily cratered object in
the Solar System.

r:;:-=-- --





' lo is the So\at' S'istem's .
t \/o\canica\\y acti\/e moon. Mored
inoS ~50 volcanoes spew yellow, red a_n
t\1a\ ulphur onto its surface. One ot ,ts
b\ac s Lol<i gives out more neat t\1an
\canoes,
b' d
'
vo t earth's active volcanoes com me .
all o ic
shoot p\u\l\e<l ol/ sulphur up to
,. 'io\canoes
-,oo \<.l\o\l\etres a\,cNe lo.










'J foUe of Jupitee'
S~al/e,-. frlOOhS Cil"c/e the s
g,aht withih 10 , . sas
called Metis Ad S O/'brt. They are
, rastea A Ith
Thebe All ' ma ea and
. are odd shapes
don't have th , as they
round, circu/a~ s;::.needed to form a


-c::..

\.9) ib f:ul"o,=>a is covet'ed with
unusually smooth ice. Scientists think
the ice may be floating on an ocean of
water, which is kept from freezing by the
heat inside Europa. This ocean could be
around 100 kilometres deep, and could
contain life if conditions are right. In the
future, probes may
explore Europa's
ocean for signs
of life. • Jup;fer's
Sh"- "1oon ..
,.,, ~Yeq 'Ni'/1, n"1a/11,ea
SUiphur f "1qy be req
rorr, Vo/can because ·t .
oes on lo. I IS

Remarkable rings






6 4 Saturn i9 the Solar 9ystern's seco nd biggeS t
planet. It is surrounded by huge, shining rings. Like Jupiter,
Saturn is made almost completely of hydrogen and helium.
Below its thin atmosphere, these gases _are compressed

so much that they become liquid.


<;ctrurn gets its colour
from sulphur in its
atinosrhere




The total widtt, ol' Saturn's r,ng,
is abovt three-quarters
ol' the distar<:e from Earlh to
' Saturn spins so rast the Moon, but they are only a
that it bulges ouiwards at l'ew hundred meir-e<3 thick
'li,e middle.




6 5 MilliohS of ice par-ticles rnake up
Satut-h'S t-ihgS. This is what makes them so bright.
They _orbit the planet like tiny moons reflecting sunlight.
The nngs are thought to be the remains of destroyed
moons, comets or asteroids.













The ice in Saturn's
rings ranges in size
rrom specks smaller
tt,an a grain or sand
to huge chunks.

'' Like the ofh
giants, $ah.it-ti's up er- sas
~lows ar-ound the Pf:: ;~ospher-e
1
This means that gas is e n bands.
at high speed f mo~ed around
-~ , orm1ng huge
.
to
is ome
. ·•.. . storms. Saturn . h
· ' many storms
; including va~t
hurricanes at
\ its poles.
\



r:r-


.J / If you could find a bi9
enough bath of watet-, Saturn
would float in it. This is because
despite its huge size, it has the lowest
density of all the planets.

Gape; and bends in the
rinss are caused l,y the
"°"llof9"Q'Jltyfrom
nearby moons
.... .l ' r. .

SRlUP.n r- '
I,
t fi\E: \tur11.
Fat d of agricU Earth) j 1.
r,oman g o ,9 _5 t1 ·riws
. 1h11. tr11.s l .
ed after. 536 ki\ome 34 million
8££11,~ narn ter: 1'20, sun: 14
- the
O ·arne
'
fro, ..
Wheh Galileo first looked at Oistanc\s . 10.7 hours
-
. once.
Saturh through his telescope ,,·1om11.tr spin sun: -~
.,,
ih 1610, he mistook the 'Ti\112 ta aru -..,_,
'-it the
irne ta
p/ahet's rihgs for 'T 4 y11.ars rature- .
two moohs. 29. t2rnP2
A112fll91Z 62
4
-1 0°[ of rno ans: .,...
.JI
nurn1:>2r

Sc~urn's moans


r,'.
..


: 68 Saturn has nearly 6 9 Some Saturn's moons orbit
, as many moons as Jupiter. Inside its rings. These are called shepherd
moons because they herd the ring particles
So far, 62 have been
together, like a shepherd keeping a flock of
, confirmed. Saturn and its sheep together. Shepherd moons give Saturn's
•
• moons were explored by rings sharper edges.
1 the Cassini spacecraft, " Satur,n•s she h
Ct'eQte the Cl p el'cl moons, such <IS
which arrived at Saturn g Ps In the Pl<1net•s ftH<1s Shown her,e
<1mo11s Nngs. '
in 2004. It discovered
., moons that are too small

· to be seen from Earth.
t .
.
j
\ .
I
I
1/ 0 Titan, saturn'C3 I • -
l
\argec,t 1noon, iC3 'oigger i
than Mercury. It is the only
• moon in the Solar System with
' a thick atmosphere. Since its
arrival, Cassini's observations
have allowed scientists to
discover much more about the
solid surface hidden below
Titan's atmosphere.
The Ca,,ini spacecraH ~\ew through
a 9ap in ~rn's rings \,~ore 9oin9 into
orbit around the planet.















'34

wr:s s


has been exp/of"ing c--1-..
and ·t ;x.i,urn
,1 The l'.uro~eao S~ace flger,cy laoded a , s moons since zoo47
mini-probe called Huygeng on Titan in 'Z-005. Z. What is the name .n "'"'-
Tor , ne
moon "'"'-
It was carried to Saturn by the Cassini spacecraft. s , nat Of"bit inside
Huygens found lakes on Titan, but instead of water Saturn's f"ihgs?
they're filled with chemicals including ethane and 3. Which o-P Sa-1-. ·rh'
.
,u s moons
methane. Huygens also carried a microphone that 1 s the biggest'(
picked up the sound of wind blowing on the moon.
This was the first sound ever recorded on another
planetary body.

descended thro119h
/'IS Huy9en<; ran9e-brov,n Satvr-n's moon
~tcln'S ha'tY o rds the surrace, as it Is cover-eel
" h e tov,Cl
atinoSI' er recorded the viev,. ci into SJ>ace fr-om
its cameras eteor-o;c1s.











•s "'oon
• saturn oo\:,s \i\<.e a
\\yperion I ause it iS
gpanse ~i'l\l \ots di
covered -edsed
dee!', sne1rp
craterS-
enceladus has an icy surface
that inay have an ocean o\! lictuid
v,ater underneath. Geysers shoot
Jets o\! v,ater va1>our and ice high
above the surface o\! the tnoon.




n Saturn's frlOOhS are arria-zingly
varied. They differ greatly in shape and
size, and have different types of
surfaces. Cassini has explor~d these
moons in great detail, allowing
scientists to study them more closely.



'35

A blue-green world







73 Ur-anus, the Dark, qugty rit,gs

sevehth plahet rr,orn /
the Suh, is about
. tour, times bigger,

thah Ear,th. It has
an atmosphere of

hydrogen and
heliu
an ocean of liquid ~ 1

water, ammonia , J Unlike the
er J:>lanets, Uranus SJ:>ins
and methane its side. This means that one
' surrounding a le faces the Sun for 42 years and
n the other pole faces the Sun for
rocky core. ears. Scientists think that Uranus
have been knocked onto its side
en an Earth-sized object crashed
I DON'T BE.LIE.VE. IT! o it while it was forming.
When Uranus was discovered in l'<lnus has 13 rings. They r-e-\!lect
, \18\, it was almost named Georg~uV. light than Saturn's rings, so
not as easily seen.
c;;du, (Georgian planet) a~ King
George7' 11-ot-Great'~ritain.
Uranus was instead chosen,
atter the ancient Greek
god the sky. ~ =~;;;;;;;;;;:











The Voyager 111ulfiplanet 1111ss10n
was ofriclally appr-oveq, anq work
began to buflq Voyager t anq its
twin, Voyager /.

-


M~med after: The Greek god of the sky
Ur-anus has
Diameter: 51,118 kilometres (<i.0 times Earth)
biggest moon, Titania, is less than
D_istance from the Sun: 28i'3 million
the size of our Moon. Even though it is kilometres
so small, it was spotted as long ago as Time to spin once: li'.2 hours
1787 by the astronomer William Time to orbit the Sun:
83.i' years
Herschel, who also discovered Uranus. R erage temperature:
11
-195°[
number of moons: 2i'

.., Only one spacecM\'t has
'
visited Ur-anus - Voyager~- It left Earth
in 1977 and arrived at Uranus 11 years later
in 1986. It is still the only spacecraft to have 'Y Voyager :i discovered ihat U~nus has
visited all four of the gas giants. a tilted magnetic tie\d. It also discovered
ten OT i't9 moons and n,,o OT i't9 rings.






















'31

The F' arthest planet





r-r-

/ I The lac;t of the Solar Syc;tern'c;
eight planetc; ic; Neptune. It is the
smallest of the gas giants, but still

nearly four times bigger than Earth.
, Like Uranus, it is an icy world made

of hydrogen and helium, as well as
water, ammonia and methane.




7 8 Neptune was the rir-st planet round . '
. )_i;ir,
by mathematics. Astronomers noticed that Uranus .. :J-4,.. ...... ...
.
was being tugged by the gravity of another large '''\1~ ·•
, body, which affected its orbit. Calculations showed
astronomers where to look, and in 1846, Neptune
was found.

fact file: nePTUnE



named after: The P.oman god of the sea Neprune's blue
Diameter: 49,528 kilometres (3.9 times Earth) colour is caused by
Distance tram the Sun: 4495 million kilometres methane in its
atmosphere.
Time to spin once: 16.1 hours
Time to orbit the Sun: 164 years
Average temperature: -200°[ • C\audc.. on t;ar"lt, are
number of moons: 14 tn<1de 'llater, 1,ut
Neptune'C.. clouds are made
chemica\c, including
ine"lt,ane, am111onia and
r-r hycll'O'ilen c,ulphide.

/ / Neptune's winds ar-e the rastest in the
Solar- System. They race around Neptune at almost
2400 kilometres an hour. It is thought that heat
bubbling up from Neptune's core creates these winds.
Neptune's surface is also streaked with clouds, high in
the atmosphere.

rk Spot was a giant super-
A Neptune'? Gre:-~:kwise once e\Jet"f 16 days.
stor111 spinning an

80 When Voyager ;i: l'f,ot091'<lphed
Neptune in 1989, it captur-ed a lar-ge dal"k
stor-m as big as far-th. The storm was called
the Great Dark Spot. But when the Hubble Space
Telescope was turned towards Neptune in 1994,
the Great Dark Spot had disappeared.




8 f Ne~time hos l"I "'°"n;, fo\11' of which
ar-e shepher-d moons. The biggest, Triton, was
discovered just 17 days after Neptune itself. Triton is
so cold that it has ice volcanoes shooting out a
mixture of liquid nitrogen, methane and dust.


Triton's su~ace is co\Jet-ed with frcn:en
nitrogen, a gas found on earth.




I DOIV'T 8££i£V£ IT!
Neptune was discovered to
be a planet in 1846, but it
was first seen by the great
astr-onomer, Galileo Galilei,
Z'34 years earlier. Galileo
thought he was looking at
a star, not a planet.

Distant travellers






A co111et is a 111ountain o-1' rocl: and
ice orbiting the Sun. Most comets are too far
away for us to see, but occasionally they come
closer to the Sun. The sun's heat changes some
of the ice into gas. Gas and dust flying off the

comet form long, bright tails.

'f Tue cloud or cotna around a cotnet iS tnade en dust and gas.
Pust tortnS one en the cotnet's tails and gas tortnS a second tail.



























si ;comet'9
te1i\9 e1\wC1Y9 ?oint
e1wctY from the Sun.
:Z When the comet
sunlight and particles 11\0\/es away ft-otn the
streaming away from Sun, ,ts tails fade
the sun - called the
solar wind - sweep
the tails back, away
from the sun.

(\ comet's tails can 't>e
\onger than the distance
trotn the t;arth to the sun.

lo 199"1, a co•et sla••ed ioto
the giant j:>lanet Juj:>iter. The comet was
called Shoemaker-Levy 9. As it headed for
Jupiter, it broke up. One after another, the
pieces of the comet hurtled into Jupiter's
atmosphere at more than 200 times the
speed of a jet airliner, creating fireballs and
huge dust clouds.

Pieces ShoeMker Levy 9 heacl
~or Jupiter like a strihg pearls.

as The whole Sola, Syste• .ay be
A 'star' with a long tail
surrounded by millions o¥ comets) Scientists think
that some of the comets we see come from a vast cloud apr,eared Just betore the
of icy rocks that surrounds the entire Solar System. It'~ Battle o¥ Hastings in
called the Oort Cloud. Others come from a closer region 1066. It was actually a
outside Neptune, called the Kuiper Belt. comet The English king,
Harold II, thought it was
a Sign o¥ bad
luck. He was
right - he
lost the
battle/







a, The co111ets we see
troll! tillle to ti111e si,end only a
tiny i,art or their orbit n~ar the
Sun. The rest of the time, their long,
thin orbit takes them far away to the
outer reaches of the Solar System.
These can take thousands of years to
4 orbit the Sun. Some comets get caught
Comet 6rP appears ih the sky every 6-1 years. Oh l'.Z
Novem~r :Z.014, the f:uropeah Space /lgehcy's Rosetta spacecraft up in much smaller orbits and appear
illacle history by lahclihg a probe, Philae, Oh the comet. This image every few years.
was takeh by Philae durihg its desceht


41

Dwarf' planets

' I I • I


cr- 2 6 3
2326 200
rJ" I Dwarf planets are

sinall worlds orbiting the
Sun that are not big
enough to be classed as
.t. These are the first five dwa,-f r,Janets to
planets. There are five be oftlclally recognized. More discoveries are
cet-ta1n to follow.
'official' dwarf planets, but

a\<.eS \eSS tt,an
'f Ceres t to orl>it the
found and may soon join •·-ie years h •urther
11 sun. Eris, 111UC 1
s years.
the dwarf planet club. tal<eS S 1
QIN a'/ '
r; r;
1 1
., .., Pluto was a planet for
16 years. When Pluto was discovered
in 1930, it became the Solar System's
ninth planet. But when astronomers
started finding more smaller worlds like
Pluto, they decided to call them dwarf
planets. So in 2006, Pluto became a
, dwarf planet. Pluto's orbit is oval-
shaped, sometimes
" crossing inside
Neptune's orbit.







Dwal'i r,lanet
Pluto has five
moons. The biggest
is called Chal'On. A even though it
sr,acecraft called New is so far away,
Horizon, will arrive at Makemake reflects
Pluto in 1-015 to stucly Just enough sunlight
the clwal'i r,lanet ancl its to be seen by large
moons for the first time. telescor,es on earth.

8 9 Only one d~ pldnet hc:19 i,een found
Ceres 111ay have a
deep Jayer oi ice under ih the Asteroid Seit between Mars and
rts tt,in, dusty crust. Jur:,iter. It's called Ceres, and it is also classed as the
largest asteroid. The other dwarf planets orbit the
Sun in the Kuiper Belt, beyond the farthest planets.

r;r;


/ f:ris' discovery
made astronomers
rethink Pluto's
status as a planet.
Eris has more mass
than Pluto, so both
were classed as dwarf
planets. Eris is the most
distant dwarf planet,
made of rock and ice .




.a. \:ris has a tiny
11100n called Dysno111ia. I. When was Pluto
In Greek 111ythology, ctiscovered'il
Dysno111ia was the
daughter OT the z. Which dwar.P planet is
Greek god \:ris. bigger than Pluto'{
3. Which dwar.P planet is
.Purther .Prom the Sun -
Haumea or Makemake'il
tlau111ea 111ay
have been set
spinning very 9 J Dwarf planet
tast when Haumea is a very strange
so111ethin9
crashed into shape. It spins so fast, once every
it Millions OT four hours, that it has stretched out into
years 090. the shape of an American football.
Further out from Haumea, Makemake's
surface has large amounts of solid frozen
methane, found as a gas on Earth.

The search For \if'e





•. 'h. DOrl"r 8££f £V£ ,r,
vv1 en the Apo//4
•
9 2 Serot'e the space age, retu,..n-.J .1\ 0 11 astrona, ,4.,,.
=« Tf"Ofrl the f' ,..,
"'I::;
some people thought landing, they had ti ,,..~' Moon j
intelligent cr-eatut'eS liVed on hazar-d sutts aticl ti o wea,.. bi~
chdmf ,/Wlfi a SJJecial
Mars. So far, life has not been 111 case the
found on Mars or anywhere had brought back y
dangerous micro::~
else in the Solar System, but
scientists are still searching.



• 'The Curior;tfy r011er landed in Gale
9 J Two Viking spacecraft landed on Crater on Mar<, on Ii f,.ugust, 1-01-i.
Mars in 1916 to look tor si9ns ot lite. When
they tested the Martian soil, the results seemed to
show signs of microscopic living organisms.
However, scientists decided that the chemical
activity found was not evidence of Martian life. In
2013, the Curiosity rover found evidence in Gale
Crater of an environment that could have
supported microscopic life billions of years ago.


















When Viking :i landed on
I Mars in 191/i, its cal!!eras
looked out on a rock-
strewn ,,art en the i,lanet
t ;! called Utoi,ian Plain.

1
::._ SJF:WIZ PJRRlf75mzr:,;;;¥
l * M = mrve EZIF?':;
'

® In 19·9{,, scientists
thou9ht they rnay have rinally
round si9ns or Martian lire.
They discovered worm-like
features in a meteorite from Mars
that looked like microscopic fossils
of bacteria. But other scientists
disagreed. It will take more
exploration to know for definite if
life ever existed on Mars.
jhese worro-\i\c.e
.... ,res were round
.
-"
!reel•'-' roeteor1te ,roro
·d
inS1 e O
f'tl<lr5 disco\/ered neor
...,_,,.. soufu Pole.
eor111,


9 5 LJfe in tl,e Sola• System was
previously thou9ht to only be possible in a
narrow \,and called the 'Goldilocks tone'.
But now scientists think life could exist elsewhere.
one of the most promising possibilities is Jupiter's
moon Europa, where there is thought to be an
ocean of water underneath its icy surface.













The '.2.013 reafur-e
I Ill, europo Report.
tells the stor-y or '
rictional lllatinecl ,,::,,
Ill. . ,,..~ce
1ss1on to Jupiter-'s
llloon, tur-opa.

The Soler System's F'uture








96 /n the distant future,
the Mooh will look much
small er to our descehdahts.

This is because its orbit is
slowly increasing in size,

moving it away from Earth.
Every year the Moon moves
about 3.8 centimetres further
away from us.

The Moon is
T Hl9h tides on Earth are slowly spirallin9
speedin9 up the Moon, causin9 it away rrom Earth.
to ll!Ol/e turther away rrorr, Earth.

key Moon's
orbit
@ The Moon's gravity raises a
bulge OT water on l:arih
tnUC ur
• The spinning Earth drags the . w ·\\ the Moon 'o
water ahead OT the Moon
rotn ee1rth w~ trotn now?
@ The water pulls on the , ten 'leelr ·\\ the sun 'oe
Moon, speeding it up and , ' \J,Jhe1t co\our w1 1
increasing its orbit ,' . ·t swe\\s up
1 , , when. i d ot ste1r wi\\ the
, , \J,Jhe1t kin ?
. S~n tine1\\'f 't,eCO\!le

µl!MP .ll\l\M 'v' "£ .
.l'l\ "l. S.lJ+.llll\lU.lJ 8£
p :SJ.lMSU'/
Earth's rotation




91 The Suh is geadually
growing bigger and brighter. This
is because the amount of hydrogen
gas in the Sun is decreasing over
time. In about a billion years, it will
begin to evaporate Earth's oceans.



46

98 /h about four billioh years,
ct 9ctlctctic collision will take place.
The Milky Way galaxy that includes our
Solar System will collide with neighbouring
Andromeda galaxy, although Earth and
the Solar System should survive.

When the Milky Way and Andromeda galaxies
meet, they will merge together to form one
enormous new galaxy.





99 /lb01Jt five billioh
yectr9 -rrom now, the Sun
will run out or hydt-ogen
and other -ruels it needs.
Nuclear fusion will stop. The
sun will swell up into a
massive red giant star and
cool down.


The red giant Sun will be over ZOO
ttmes bigger than the Sun today - big
enough to swallow the closest planets,
perhaps including t:arth.







V ® ® The red giaht stCll'
will eventually blow away its
outer layers or 9cts. This will
leave a glowing halo of gas around
the star. The remaining star will then
shrink to become a tiny white dwarf.
The white dwarf will cool and fade
away over billions of years.

The cloud or gas that will surround the
shrinking Sun iS called a planetary nebula.