Do all planets have satellites?
Mercury and Venus have no satellites. Earth has one satellite (the Moon), Mars and Neptune have two satellites each. Uranus has five satellites. Jupiter and Saturn have a large number of satellites. Pluto has one satellite.
Can a satellite be larger than a planet?
A satellite is much smaller than the planet around which it revolves. However, a large planet is capable of having a large satellite. Titan, one of the satellites of Satum, and Triton, a satellite of Neptune, are larger than the planets Mercury or Pluto.
Does the period of spinning remain the same for all the planets?
The day of each planet is different. For example, the period of one day for Mercury is 59 Earth days; for Venus, it is 243 Earth days and for Mars, it is about 24-1/2 Earth hours. Thus a large variation in the period of spinning is due to random collisions with comets and asteroids over very long periods.