Mercury
CategoryInner Planet
SystemSolar System
Diameter4879 km
Orbital Period88 days
About Mercury
Terrestrial rocky planet closest to the Sun. Surface temperatures swing from -180C at night to 430C during the day, the largest range of any planet. Has virtually no atmosphere, just a thin exosphere. The Caloris Basin is 1,550 km across, one of the largest impact craters in the solar system. Has a massive iron core making up 75 percent of its radius.