Mercury is a very small planet, with a surface that is exposed directly to space. This is because the planet has practically no atmosphere. Normally, no atmosphere would mean very cold, but it is very hot on Mercury. Why?
A)
Since it is so small, it generates its own heat.
B)
Because Mercury is the closest planet to the sun.
C)
Because of the Mercurial volcanoes on the planets surface.
D)
Their are hot springs on the surface that constantly boil.