Ever wondered what it would be like to see a giant potato in the sky? If Elon Musk ever gets humanity to Mars, we may find just find out. The Red Planet has not one, but two potato-shaped moons in its orbit—and scientists have a new idea on how they came to be.
Phobos and Deimos. Mars’ moons were discovered by American astronomer Asaph Hall in 1877. He named the larger one “Phobos” and the smaller one “Deimos,” which mean fear and dread, a reference to the sons of the Greek god Ares. Ares the Greek counterpart to the Roman god Mars. They are some of the smallest moons in our solar system, according to NASA.
Interestingly, Phobos orbits 3,700 miles (6,000 kilometers) above the planet’s surface. To date, it is the known moon that orbits the closest to its planet. This means that if you were standing on side of Mars facing Phobos, it would take up a large part of the sky. Phobos orbits Mars three times a day, while Deimos orbits once every 30 hours.
The Martian moon Phobos.
The Martian moon Deimos.
A Martian origin story. Scientists have long speculated on the origin story of Mars’ moons. For years, there have been two main theories. One claims that Mars’ moons are asteroids that were captured by the planet’s gravity, although this theory doesn’t explain why the Phobos and Deimos have a circular, stable orbit aligned to the Martian equator.
The other proposes that Phobos and Deimos formed from a disk of debris following a giant impact, which is how Earth’s Moon formed.
The third theory. Yet, according to a new paper published in Icarus this month, the truth may be somewhere in the middle. After running hundreds of simulations of asteroids that passed by Mars, the study’s authors suggest that Phobos and Deimos formed from a huge asteroid that got too close to the Red Planet, whose gravity proceeded to tear it to shreds.
In this scenario, the remains of the asteroid temporarily formed a ring around Mars. Over time, those remains would start slamming into each other, affected by gravity from both Mars and the Sun. Eventually, the rubble that remained would clump together to form the potato moons we know today.
“They look like asteroids, they smell like asteroids, as well as looking like potatoes,” James O’Donoghue, a planetary astronomer at the University of Reading in the UK who wasn’t involved in the study, told The New York Times. He added: “What they’ve got here is really compelling, I’m sold.”
The search for answers. The new theory, while exciting, isn’t accepted yet, although we may get closer to a definite an answer in the next few years if the Japanese Space Agency’s Mars Moon Exploration mission achieves its goal. The mission, set to launch in 2026, aims to travel to Phobos and collect surface material from the moon so it can be studied on Earth.
If the sample matches the composition of Mars, it will support the theory that a giant impact formed the planet’s potato moons. But if it’s similar to that of an asteroid, it could support the new hypothesis proposed by the scientists.
“Even if this isn’t the way Mars’ moons formed in particular, it could be the way moons form around another planet,” Jacob Kegerreis, a postdoctoral researcher at NASA’s Ames Research Center who led the study, told Science News. “Now that we’re finding all these exoplanets and hopefully exomoons, it’s worth it to explore how these things could happen in different solar systems, even if not in this one.”
Images | NASA
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