Mercury Facts for Kids

The planet closest to the Sun, Mercury is the smallest and fastest planet in the solar system -- whipping around the Sun every 88 Earth days.

In Roman mythology Mercury is the god of commerce, travel and thievery. Mercury is also known as Hermes, the messenger of the Gods, in Greek mythology. The planet probably received this name because it moves so quickly across the sky.

This is the symbol for Mercury: 

Mercury is the planet closest to our Sun, and it is the eighth largest of the nine planets.

Mercury is a small, rocky planet – much like our Moon. It is covered with craters and has changed very little from when it was first formed.

One of Mercury’s largest features is called the Caloris Basin. It is about 1300 km across! It was probably created by a very large crash early in the history of the solar system.

Look for Mercury! You can see Mercury with a pair of binoculars or even the naked eye. Because it is always very near the Sun, Mercury may be hard to see in early evening skies.

Mercury Photos & Movies

  • Mercury as seen by the Mariner 10 spacecraft (mosaic)
  • A close-up view from the Mariner 10 spacecraft
  • The Caloris Basin – one of Mercury’s largest features!
  • Mercury’s Double-Ring Basin
  • Hills of Mercury
  • A large fault (crack) on Mercury’s surface
  • Mercury’s south pole – lots of craters!
  • A video clip 1 from Mercury – Exploration of a Planet
  • A video clip 2 from Mercury – Exploration of a Planet

Planet Notes

~ Mercury is a small, rocky planet.

~ Mercury has been visited by the Mariner 10 spacecraft. Mariner 10 has mapped a little less than half (45%) of Mercury’s surface.

~ Scientists think that there may be volcanic activity on Mercury. They are still studying information sent to Earth from the Mariner spacecraft to make sure.

~ The temperature on Mercury ranges from 90 K to 700 K.

~ It was once believed that there was no water on Mercury, but this turned out to be false. Recent radar information shows evidence of ice at Mercury’s north pole! The ice hasn’t melted because it is protected from the Sun’s heat by shadows of some craters.

~ Unlike many of our nine planets, Mercury has no moons.