Phobos Might Only Have 10 Million Years to Live

[Sticks]

link (http://www.universetoday.com/2008/05/13/phobos-might-only-have-10-million-years-to-live/)


You can breathe easily. The Moon is slowly receding away from the Earth at a rate of 3.7 cm/year (1.5 in/yr). But the Martians aren't so lucky. Their moon Phobos is known to be doing exactly the opposite. It's spiraling inward, and in the distant future it will crash into the surface of Mars.


:shocked:

[Barbie]

this is quite intresting ... i like hearing about space
if we are expanding what into.. what causes the moon to move away from the earth.. the mars one is more understandable as its being pulled in but why is ours going out??

[Sticks]

According to the article



They key is that the material was tossed into a high enough orbit, above what's known as the synchronous orbit. This is where the Moon completes an orbit slower than the Earth takes to rotate once. Since the Moon ended up higher than this orbit, it's spiraling outward. If its orbit was less than the length of a day, it would spiral inward.