Let’s Visit: Moons of Mars — Phobos and Deimos

All you need to know about the two Martian Moons, Phobos and Deimos.

Mars Moons Phobos and Deimos
Credit: NASA

Orbiting Mars are two moons, Phobos and Deimos, with very similar surface materials to the many asteroids that make up the outer asteroid belt. In other words, Phobos and Deimos are two very big lumps of space rock — space rock with a fascinating history.

Who discovered Phobos and Deimos?

Credit: WikiData

Both moons of Mars were discovered in 1877 by American astronomer, Asaph Hall. However, what most space settlers don’t realise is that — like much of Earth’s history — there was a woman behind the discovery. 

Frustrated and deflated after years of work, Asaph was about to give up on his search for a moon that orbited the red planet. It was his wife, Angelina that encouraged him not to throw away his dreams quite yet. 

The next night, Asaph saw for the very first time (of the entire human species) the smaller of the two moons, Deimos, through the narrow viewfinder (although the best of the time) of the United States Naval Observatory (USNO) 66cm telescope. Just six nights later, he discovered Phobos.

Where do the names Phobos and Deimos come from?

phobos and deimos greek gods
Credit: Julia Van Hellen

After discovering the two Martian moons, Asaph Hall named them after twin characters from Greek mythology. Phobos and Deimos are the sons of Aphrodite, the Greek goddess associated with love, pleasure, beauty, passion and procreation, known to the Romans as Venus, and Ares — the Greek god which represents the untamed and violent aspect of war, whose Roman counterpart is Mars. 

The twins would often be depicted as horses, accompanying their father to battle. Phobos personified feelings of fear, while Deimos personified feelings of dread felt by those heading to war.

What are the characteristics of the two moons of Mars?

Moons of Mars phobos and deimos
Credit: NASA

Mars’ two moons are oddly shaped and among the smallest moons in our solar system. They are lumpy, riddled with craters, and covered with dust and loose rocks. Not sounding like a great holiday destination? Think again!

If you’re an adrenaline seeker, Phobos might actually be the place for you. As the larger of the two moons, Phobos orbits only 6,000 kilometers from the surface of Mars, that’s closer than any other moon. Not only that, Phobos whizzes around Mars at a rapid rate of three orbits a day. 

Don’t delay your visit too long, though, as the moon is gradually spiraling closer and closer to Mars; within 50 million years, Phobos will either crash or break apart and become part of the asteroid belt. Trust us, you don’t want to be taking you holiday on Phobos when that happens. 

If you’re looking for a more sedate holiday, Deimos is the moon for you. With an axis of only 16 km, Deimos is the perfect desert moon. The smaller of the two moons soars around Mars at a gentle orbit of 30 hours, around 20,000 km from the surface of the red planet, giving you glorious vistas without the fear of, well, fear (just a little Phobos humor we have around here). 

At least for now (before Phobos collides with Mars), the two moons might actually be the best place for observing the fiery red planet of Ares. From the Mars-facing side of the moons, Mars takes up nearly the entire sky, offering a perfect opportunity for surface assessment before terraforming. What’s more, you would be shielded from cosmic rays and solar radiation for nearly two-thirds of every orbit. It doesn’t get much better than that!