According to Universe Today, when Mercury is at its closest point to Earth, it is approximately 48 million miles away, and at its farthest point, Mercury is approximately 138 million miles away from Earth. This difference is due to the fact that both Mercury and the Earth orbit the sun.
Mercury is the planet that is closest to the sun and thus makes its journey around the sun more rapidly than any other planet. It is the second smallest planet in the solar system and is two-fifths the size of the Earth's diameter. Mercury takes 59 Earth days to rotate on its axis and 88 Earth days to revolve around the sun, according to Fact Monster Science.