The smallest planet and the closest to the Sun, with extreme temperatures and a heavily cratered surface.
Mercury is the smallest planet in the Solar System and the closest to the Sun. It races around the Sun in just 88 days, which is why it was named after the swift messenger of the Roman gods.
A world of extremes
Mercury has almost no atmosphere to hold heat. During the day the surface reaches about 430 °C, at night it drops to about −180 °C. Yet in deep craters near the poles, which never see sunlight, there is water ice.
Exploration
- Mariner 10 flew past Mercury three times in 1974 and 1975.
- MESSENGER orbited Mercury from 2011 to 2015 and mapped its entire surface. The map above uses enhanced colours to show differences in the composition of the rocks.
- BepiColombo, a joint mission of the European and Japanese space agencies, continues the exploration.