Something’s not quite right about the moons of Mars. They are too small — Phobos is 17 miles across, and Deimos is 9 miles in length. And they aren’t round, but lumpy, misshaped objects. Frankly, they don’t resemble moons at all. “They look like asteroids, they smell like asteroids, as well as looking like potatoes,” said James O’Donoghue, a planetary astronomer in England. Perhaps, then, astronomers have suggested, they are asteroids — two space rocks captured long ago by Mars’ gravity.
A new study makes a case that the moons did indeed start out in asteroid form. But it’s not the genesis everyone was expecting. Using computer-powered simulations, scientists describe a situation in which a large-enough asteroid was captured by Mars and torn apart by the planet’s gravity, forming a debris cloud, and maybe a ring system, around Mars that ultimately clumped together to form two moons.
The notion that Phobos and Deimos may be captured asteroids has long come up against one major problem: Their orbits are too circular, and too neatly aligned around Mars’ equator. If these moons were once asteroids, their orbits would be expected to be tilted and perhaps oval-shaped. That they aren’t supports the theory that they were forged another way. — ROBIN GEORGE ANDREWS / NYT
Oman Observer is now on the WhatsApp channel. Click here
