Mercury is the closest planet to the Sun. There is no atmosphere because of the intense solar radiation so the temperature can range from about 400°C on the light side to below -100°C on the dark side.

The surface of mercury is heavily cratered, having an appearance similar to the moon.

The length of a day on Mercury is just under 116 earth days, which is longer than a year on Mercury. This strange fact happens because Mercury is locked in a spin-orbit resonance with the Sun (similar to the way we only see one side of the Moon from the Earth).

Mercury has been visited by two space probes: Mariner 10 and Messenger. These have provided us with good images of the surface of Mercury. It is not really possible to see any detail of Mercury from earth-based telescopes because of the closeness to the Sun and bright light

Even though sunlight on Mercury is very bright, there is thought to be a large amount of water, in the form of ice on the planet. This is located in deep craters in the polar regions where direct sunlight never penetrates