The Terrestrial Planets

The Terrestrial planets have each passed through 4 stages of evolution

What controls the severity of each phase?

Mercury
Planet Mercury, with a mottled brown surface. 		Venus
Planet Venus, with a red and black surface with strands of gold. 		Earth
Planet Earth, with streaks and wisps of white clouds above a blue ocean. 		Moon
The Earth's natural satellite Luna (the Moon), with a heavily cratered stark brown and yellow surface.		 Mars
Planet Mars, with a reddish surface interrupted by large dark patches and by bright white patches at the pole.
Images of the Terrestrial planets and Earth's Moon. [NASA]