How bright are the moons of Mars from its surface?
Phobos is close enough to Mars (3720 km) that it appears as a disk about 2/3 the diameter of our moon, and has a brightness about 40 times that of Venus in our sky. It takes only 4 hours to travel across the sky from horizon to horizon. Deimos is more distant and fainter, about as bright as Venus, and takes 60 hours to travel from horizon to horizon.
