Solar System GEEC

What is solar system?
The sun together with the eight
planets and all other celestial

bodies that orbit the sun.

This is how our solar system look like.

How many planets are there in the Solar System in 2021?
There are eight planets in the Solar System according to
the IAU definition. In order of increasing distance from
the Sun, they are the four terrestrials, Mercury, Venus,
Earth, and Mars. Then the four giant planets, Jupiter,
Saturn, Uranus, and Neptune.

Who is IAU?

The International Astronomical Union (IAU) was founded
in 1919. Its mission is to promote and safeguard the
science of astronomy in all its aspects, including
research, communication, education and development,
through international cooperation.

Solar System Planets: Order of the 8 (or 9) Planets

Four terrestrials
Mercury

Mercury is the smallest planet in our solar system. It’s a little
bigger than Earth’s Moon. It is the closest planet to the Sun, but
it’s actually not the hottest. Venus is hotter.

Along with Venus, Earth, and Mars, Mercury is one of the rocky
planets. It has a solid surface that is covered with craters like
our Moon. It has a thin atmosphere, and it doesn’t have any
moons.

Mercury likes to keep things simple. Mercury spins slowly
compared to Earth, so one day lasts a long time. Mercury takes
59 Earth days to make one full rotation.

But a year on Mercury goes fast. Because it’s the closest planet
to the sun, it goes around the Sun in just 88 Earth days.

Venus

Venus is the second planet from the Sun and Earth’s closest
planetary neighbor. Even though Mercury is closer to the Sun,
Venus is the hottest planet in our solar system.

Its thick atmosphere is full of the greenhouse gas carbon
dioxide, and it has clouds of sulfuric acid. The atmosphere traps
heat, making it feel like a furnace on the surface. It’s so hot on
Venus, the metal lead would melt.

Venus is sometimes called Earth’s twin because it’s similar in
size and structure, but the planets are very different in other
ways.

In addition to being extremely hot, Venus is unusual because it
spins in the opposite direction of Earth and most other planets.
It also has a very slow rotation making its day longer than its
year.

Earth

Our home planet Earth is a rocky, terrestrial planet. It has a
solid and active surface with mountains, valleys, canyons,
plains and so much more. Earth is special because it is an
ocean planet.

Water covers 70% of Earth's surface. Earth's atmosphere is
made mostly of nitrogen and has plenty of oxygen for us to
breathe. The atmosphere also protects us from incoming
meteoroids, most of which break up before they can hit the
surface.

Mars

Mars is a cold desert world. It is half the size of Earth. Mars is
sometimes called the Red Planet. It's red because of rusty iron in
the ground.

Like Earth, Mars has seasons, polar ice caps, volcanoes,
canyons, and weather. It has a very thin atmosphere made of
carbon dioxide, nitrogen, and argon.

There are signs of ancient floods on Mars, but now water mostly
exists in icy dirt and thin clouds. On some Martian hillsides,
there is evidence of liquid salty water in the ground.

Four Giant Planets
Jupiter

Jupiter is the biggest planet in our solar system. It's similar to a
star, but it never got big enough to start burning. Jupiter is
covered in swirling cloud stripes.

It has big storms like the Great Red Spot, which has been going
for hundreds of years. Jupiter is a gas giant and doesn't have a
solid surface, but it may have a solid inner core about the size of
Earth. Jupiter also has rings, but they're too faint to see very
well.

Saturn

Saturn isn’t the only planet to have rings, but it
definitely has the most beautiful ones. The rings we
see are made of groups of tiny ringlets that
surround Saturn.

They’re made of chunks of ice and rock. Like
Jupiter, Saturn is mostly a ball of hydrogen and
helium.

Uranus

Uranus is made of water, methane, and ammonia
fluids above a small rocky center. Its atmosphere
is made of hydrogen and helium like Jupiter and
Saturn, but it also has methane.

The methane makes Uranus blue. Uranus also has
faint rings. The inner rings are narrow and dark.
The outer rings are brightly colored and easier to
see.

Like Venus, Uranus rotates in the opposite
direction as most other planets. And unlike any
other planet, Uranus rotates on its side.

Neptune

Neptune is dark, cold, and very windy. It's the last
of the planets in our solar system. It's more than
30 times as far from the Sun as Earth is. Neptune is
very similar to Uranus.

It's made of a thick soup of water, ammonia, and
methane over an Earth-sized solid center. Its
atmosphere is made of hydrogen, helium, and
methane.

The methane gives Neptune the same blue color as
Uranus. Neptune has six rings, but they're very
hard to see.

Reference

Hawkes. C. (n.d.). Solar-system meaning. Your Dictionary.
https://www.yourdictionary.com/solar-system

Lowe. S & North. C. (n.d.). How many planets are there in the Solar System? Cosmos.
https://cosmos-book.github.io/how-many-planets/

Barnett. A. (n.d). Kid-Friendly Mercury. NASA Solar System Exploration.
https://solarsystem.nasa.gov/planets/mercury/overview/#otp_kid-friendly_mercury

Barnett. A. (n.d). Kid-Friendly Venus. NASA Solar System Exploration.
https://solarsystem.nasa.gov/planets/venus/overview/#otp_kid-friendly_venus

Reference

Barnett. A. (n.d). Kid-Friendly Earth. NASA Solar System Exploration.
https://solarsystem.nasa.gov/planets/venus/overview/#otp_kid-friendly_earth

Barnett. A. (n.d). Kid-Friendly Mars. NASA Solar System Exploration.
https://solarsystem.nasa.gov/planets/venus/overview/#otp_kid-friendly_mars

Barnett. A. (n.d). Kid-Friendly Jupiter. NASA Solar System Exploration.
https://solarsystem.nasa.gov/planets/venus/overview/#otp_kid-friendly_jupiter

Barnett. A. (n.d). Kid-Friendly Saturn. NASA Solar System Exploration.
https://solarsystem.nasa.gov/planets/venus/overview/#otp_kid-friendly_saturn

Reference

Barnett. A. (n.d). Kid-Friendly Uranus. NASA Solar System Exploration.
https://solarsystem.nasa.gov/planets/venus/overview/#otp_kid-friendly_uranus

Barnett. A. (n.d). Kid-Friendly Neptune. NASA Solar System Exploration.
https://solarsystem.nasa.gov/planets/venus/overview/#otp_kid-friendly_neptune

IAU International Astronomical Union. (n.d). About the IAU. IAU International
Astronomical Union. https://www.iau.org/administration/about/