Mercury is the closest planet to the Sun.
It is the smallest planet in the Solar System.
Distance from the Sun: about 58 million kilometres
Time taken to orbit the Sun: 88 days
Mercury has no satellites.
Mercury is made of iron.
What is it like on Mercury?
Dry and extremely hot during the day and freezing at night. A day on Mercury is as long as 59 Earth days, becasue the planet turns very slowly on its axis.
The surface is rocky and full of craters caused by the impact of space objects crashing into it at the time the solar system was being formed.
To astronomers in Ancient Greece this planet was known as Apollo when seen in the morning, and Hermes when seen in the evening. The planet was later named Mercury after the Roman messenger God.
The American spacecraft, Mariner 10, flew by the planet three times in 1974 and 1975. It sent back photos and has mapped bout 45 percent of the surface.