Mercury

Mercury is the first planet in our solar system. It is very close to the sun. It is also the smallest planet. Mercury is a rocky world with no air to breathe. It has lots of craters, just like our moon.

Hot and Cold

Mercury can be very hot and very cold. During the day, it gets hotter than an oven. At night, it gets colder than ice. This happens because Mercury has no thick air to keep it warm or cool. The sun heats one side, and the other side stays dark and cold.

Mercury lined up with the other rocky inner planets to compare their sizes.
Mercury lined up with the other rocky inner planets to compare their sizes. (Jamescarolinewiki / Wikimedia Commons)

A Speedy Planet

Mercury zooms around the sun faster than any other planet. It takes only 88 days to go all the way around. That means one year on Mercury is shorter than three months on Earth. But its days are long. One day on Mercury lasts about 59 Earth days.

Fun Facts

  • Mercury is named after a fast Roman god who wore winged shoes.
  • Mercury is smaller than some moons in our solar system.
  • Mercury has no moons of its own.

Did You Know?

If you weigh 60 pounds on Earth, you would weigh only about 23 pounds on Mercury because its gravity is weaker.