Mercury Mercury is the smallest of our neighboring planets. It is only one half of Earth's size. There is no air on Mercury to block out the suns extreme heat. This causes the surface temperature on Mecury to reach 400 degrees C. Mercury looks similar to out moon with its craters. The planet is barren and rocky, with little or no vegetation and no atmosphere.
Gravity is weak.
A human weighing 100 pound on Earth will weigh only 38 pounds on Mercury. The distance from Mercury to the sun is 36,000,000 miles. The planet rotates slowly. A mercury day is long, about 59 Earth days. Mercury moves swiftly around the sun.