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The moons of Mars explained.

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Mars has two moons, Phobos and Deimos.

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They are really tiny. How tiny?

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Compared to Mars or our own Moon,

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pretty tiny.

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Although ‘tiny’ is a matter of opinion.

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Their surface area is up close to some
of the smallest states on Earth,

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like Luxembourg and Malta.

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Although Phobos and Deimos are
in no way lightweight,

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in reality, their gravitational pull
isn’t even strong enough

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to bring them into spherical form.

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So they look more like huge
potatoes than moons.

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The most popular theory of their origin

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is that they were once
part of the asteroid belt,

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until Jupiter’s massive gravity
kicked them out of it,

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so Mars could catch them.

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Phobos orbits Mars at a average distance
of 9,400 kilometres, once every 7½ hours.

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It’s on a collision course, and gets
2 metres closer to Mars every year.

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In 50 to 100 million years, it will either
be ripped to pieces by Mars’s gravity

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and be transformed into a beautiful ring,

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or it will crash into Mars.

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The energy released in this collision
would kill everything on the small planet.

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So, if there are humans on Mars by then,
they should build very strong bunkers.

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Smaller Deimos, on the other
hand, is slowly escaping Mars.

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Eventually, it will fly off into space
and leave a lonely red planet behind.

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So, in a few hundred million years,
Mars will be moonless and on its own.

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Unless it manages to catch
itself another asteroid.