- from Planets
Mercury is the planet nearest to the Sun.
It’s three times closer to the Sun than Earth. This planet is hot. Its rocky, cratered surface is 800° Fahrenheit (F) during the day. At night, the temperature falls to –280°F! Mercury has been baked by the Sun for 4.5 billion years. Not long after it formed, it may have crashed into a giant asteroid. The collision blew away most of its outer covering. Today, Mercury is mostly a ball of hot iron with a thin outer crust.