01 Dec 2015
The number of ringed planets in our solar system will soon nudge up by one.
The number of ringed planets in our solar system will soon nudge up by one. Well, soon in space terms. Astronomers now believe that in around 30 million years Mars’s gravitational pull will tear its largest moon, Phobos, apart. The debris will then huddle around the Red Planet as a faint dusty ring, where it will remain for another few million years. So Mars will temporarily join all four gas planets in being circled by a ring. But then the small particles will rain down into the thin Mars atmosphere and burn up, much like meteoroids burning up in the Earth’s atmosphere.
It’s tidal forces that will be responsible for Phobos’s demise. It has been known for a while that Phobos is slowly spiralling inwards towards Mars. At first it was thought it would crash into the Martian surface. However, the latest computer models suggest otherwise. The closer it gets, the bigger the difference in gravitational pull between one side of the moon and the other. Eventually that difference will overcome the internal forces keeping Phobos together and it will get ripped to bits.
It’s just a shame none of us will be around to see it!