what is the length of a day on phobos
If you were standing on Phobos, Mars would be a significant feature in the sky, taking up almost 1/4 of the sky. How long is a day on Phobos? A day on Phobos is about 7 hours 40 minutes. How long is its orbit around Mars? Phobos is tidally locked to Mars. This means that a day on Phobos is precisely the same as the time it takes to orbit Mars. So, the same side of Phobos always faces Mars. Phobos is very close to the surface of Mars.