Archive for March 6th, 2017

Did Mars Once Have Three Moons?


(Starts With A Bang!) – Ethan Siegel:

Mars’ two moons, Phobos and Deimos, are small, irregular, but orbit in the same equatorial plane as the red planet. Although they’ve long been thought to be captured asteroids, those orbits would be supremely unlikely. Another possibility would have been if a massive impact created a debris disk, similar to how Earth’s Moon was formed. That alternative creates equatorial orbits, but normally produces at least one very large moon. However, a new simulation was performed, showing how an impact could create three moons around Mars, where the largest, inner one decays, creating the Martian system we see today. …

starts-with-a-bang 6dc076f5273d

Mars with three moons