Mars has two moons, Phobos and Deimos.

フォボスとダイモスだ

They are really tiny. How tiny?

両方とも とても小さい

Compared to Mars or our own Moon,

地球の月と比べるとこのくらい

pretty tiny.

エベレストはこのくらいだ

Although ‘tiny’ is a matter of opinion.

表面積はルクセンブルグより少なく

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

マルタより大きい

like Luxembourg and Malta.

２つともそこそこ重たいが

Although Phobos and Deimos are in no way lightweight,

重力は球形を保つほど強くないため

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

じゃがいもみたいな形をしている

to bring them into spherical form.

元々は小惑星帯にあった石だが

So they look more like huge potatoes than moons.

木星が大きくなる前に飛び出て

The most popular theory of their origin

火星がこれを捕まえた

is that they were once part of the asteroid belt,

フォボスは半径9400kmの軌道を周り

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

７時間半で一周する

so Mars could catch them.

毎年２メートル火星に近づいていて

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

５千万年から１億年後には

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

火星の重力によって壊され

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

きれいなリングとなるか

and be transformed into a beautiful ring,

火星に衝突する

or it will crash into Mars.

その衝撃はすべてを破壊するほどで

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

もしそこに人類がいたら

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

すべて灰になるだろう

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

一方ダイモスは年々遠ざかっている

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

最終的には火星を残し

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

宇宙に飛び立つだろう

Unless it manages to catch itself another asteroid.

そして火星は衛星もなく 孤独になる

Subtitles by the Amara.org community

新しくまた衛星を捕まえるかもね