Mars

Mars is the 4th planet from the Sun. It is known as the "red planet" because it appears red from the outside, due to the amount of red iron oxide Fe2O3 that exists on Mars's surface, which also causes small winds of dust around Mars's surface, causing it to appear red. Mars only has about 38% of Earth's gravity, and it has two small moons, Phobos and Deimos.

Thanks to NASA and other space agencies, water has been proven to exist on Mars, on the poles, under rocks, on the surface and on the sub-surface of the dusty red planet. Potential microbes can exist on Mars. NASA claimed that mars has fossils possible bacteria-like microbes. Similar findings have been found on the surface surface of the Moon and Mercury.

Surface
The surface on Mars is rocky, with a lot of canyons, volcanos and craters everywhere. The average surface temperature of Mars is -62 degrees celsius, but there is red dust that covers most of its surface, giving Mars the red look. This red dust sometimes causes dust storms because Mars has wind and clouds, despite the fact that Mars's atmosphere is 100 times thinner than Earth's is.

Mars, just like Earth, has seasons. That's right, seasons exist on Mars. But, the difference between Earth's and Mars's seasons are that Mars's seasons are much colder. During summer for example, Earth's temperature rises up to 45°C, while on Mars it's barely 0°C, where water freezes. Mars has no magnetic field and thus no atmosphere, so it's much colder than Earth. According to NASA and missions, there is methane on the surface of Mars.

Composition
Mars is composed of crust, mantle and a core, just like Earth. The composition of Mars, as we will see bellow is similar to that of Earth, but at the same time, very different too. Mars is basically a smaller version of Earth, but also differs in certain ways.

Crust
The crust is around 10 - 50 km thick, composed of a volcanic basalt rock and covered in a fine talcum powder. Landslides in the crust speed up the crust to hundreds of kilometers an hour (up to 725 km/h). Mars's crust isn't nearly as thick as that of Earth, but Earth's crust does get thinner in certain locations.

Mantle
The mantle has been dormant, seeing no volcanic activity for millions or even billions of years, probably. It is made primarily out of silicon, oxygen, iron and magnesium. It also contains methane, as well as red dust and iron oxide Fe2O3 and it is theorized to have the consistency of a rocky-paste.

Mars's mantle goes from the crust to a depth of around 1,200 to even 1,900 km down, very deep into Mars's internal structure, where it meets the core. The mantle is solid, but of course the deeper and closer to Mars's core it goes, he hotter it gets.

Core
Similarly to Earth, the core of Mars is solid, comprised of iron, nickel and sulfur.

Sadly, the core of Mars isn't moving, therefore, Mars doesn't have a very strong magnetosphere and lacks hospitability. However, water found on the surface of Mars suggests that small organisms may have thrived on Mars in the past anyways. The core of Mars's is possibly larger than that of Earth, but still, Mars's magnetic field is lost, making Mars uninhabitable.

Atmosphere
Mars has an atmosphere 100 times thinner than Earth's, and the atmosphere is very light, humid and wet. It consists if about 95% carbon dioxide, but there are also small amounts of nitrogen, argon, oxygen and also a little carbon monoxide too. The oxygen, argon and nitrogen on the atmosphere of Mars are very rare.

Mars used to have a thick enough atmosphere for water to run its surface. However, Mars' atmosphere is about 100x thinner than Earth's is. That's because, as already mentioned above, the core of Mars is not moving, meaning that Mars has no magnetic field. Because of this, Solar Winds emitted from the Sun, blew out the atmosphere of Mars almost completely. This event happened nearly 3,9 to 4 billion years ago.

Mars possibly had life 4 billion years ago or so.

Moons
Both Phobos and Deimos were likely 2 very small asteroids that were orbiting the Sun in the asteroid belt. So it's possible that Mars's gravity took the 2 small moons from the asteroid belt.

Phobos
The innermost and largest moon of the two. Discovered in 1877, it is a pile of rocks which have coalesced, held together by a thin layer of crust. Phobos, since it is the closest, and maybe a little bit too close, has its crust getting torn apart by tidal forces. In roughly the same amount of time it'll tale Earth's moon to stray away far enough for total solar eclipses to become impossible, Phobos will get near enough to get torn completely apart by Mars' tidal forces. This will either make it collide with Mars, or turn it into a planetary ring, like that of Saturn. Phobos orbits Mars 3 times a dat and is 17 km wide.

Deimos
Deimos is the smallest and furthermost moon of Mars. Discovered in 1877, by the same guy named Asaph Hall, it is a very asteroid-like moon, having many characteristics of an asteroids, which is quite possibly what it used to be, eventually get somehow caught by Mars. Whilst having many craters, big ones and small ones, only two completely random craters have been named, for some reason. Deimos is composed of rock and carbonaceous material, much like an asteroid. But unlike one, it is very smooth, considerably smoother than Phobos. Deimos orbits Mars in 30 hours and is 15 km wide.

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