How far away are the moons Phobos and Deimos from Mars.
The moons are very close to Mars. Deimos is about 20,000 km away and Phobos is less than 6,000 km away.
Name the English satirical writer who predicted the existence of the moons of Mars?
Johnathan Swift predicted the existence and the characteristics of the moons of Mars in his book Gullivers Travels, 142 years before the moons were discovered.
What is unusual about the period of revolution of the two moons of Mars?
Phobos orbits once in 7 hours and 40 minutes and Deimos once in 30 hours. The inner moon Phobos orbits the planet faster than the spinning motion of the planet. The outer moon Deimos remains above a given landscape for nearly three days passing through all its phases twice.
Phobos not only rises in the sets and in the east but it rises and sets twice each day. It is thought to be an asteroid captured by Mar’s gravity.
What is the synodic orbital period of a planetary moon?
The synodic period of a planetary moon is the period from one new moon to the next. For the moons of Mars it is 7 hours 39 minutes and 21 minutes for Deimos.
What is the apparent retrograde motion of a planet?
All the planets exhibit direct motion around the Sun. However, planets like Venus, Mercury or Mars can exhibit an occasional apparent retrograde motion when viewed in the sky from the earth, relative to the background of stars. This is due to the relative positions of the Earth and the planet as they orbit around the Sun.
What are planetary perturbations?
Perturbations are the changes in the path of a planet or comet or asteroid around the Sun, due to the gravitational pulls of the other planets acting on it. The main culprits in this case are Jupiter and Saturn which have tremendous gravitational fields.