SETI Institute | 2020 Jun 01
Scientists from the SETI Institute and Purdue University have found that the only way to produce Deimos’s unusually tilted orbit is for Mars to have had a ring billions of years ago. While some of the more massive planets in our solar system have giant rings and numerous big moons, Mars only has two small, misshapen moons, Phobos and Deimos. Although these moons are small, their peculiar orbits hide important secrets about their past.
For a long time, scientists believed that Mars's two moons, discovered in 1877, were captured asteroids. However, since their orbits are almost in the same plane as Mars’s equator, that the moons must have formed at the same time as Mars. But the orbit of the smaller, more distant moon Deimos is tilted by two degrees.
“The fact that Deimos’s orbit is not exactly in plane with Mars’s equator was considered unimportant, and nobody cared to try to explain it,” says lead author Matija Ćuk, a research scientist at the SETI Institute. “But once we had a big new idea and we looked at it with new eyes, Deimos’s orbital tilt revealed its big secret.” ...
Evidence for a Past Martian Ring from the Orbital Inclination of Deimos ~ Matija Ćuk et al
- arXiv.org > astro-ph > arXiv:2006.00645 > 01 Jun 2020