Mercury Facts for Kids

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The First Planet

Mercury is the smallest planet in the solar system and also the closest to the Sun. Its orbit around the Sun takes only about 88 days, which is the shortest of all planets in the solar system. Its surface has many craters, much like the Moon, and it has almost no atmosphere to retain heat. Temperatures on Mercury can range from −173 °C all the way to 427 °C. The planet is named after the Roman god of the same name, who was the god of shopkeepers, merchants, travelers, and tricksters.

Cool Facts About Mercury

  • Only two spacecraft have ever made it to Mercury: Mariner 10 in 1974 and MESSENGER in 2004. Another, the BepiColombo is planned to visit Mercury in 2025.
  • Because Mercury has less gravitational pull than earth, on Mercury you would weigh only about 38% of what you weigh on earth.
  • One day on Mercury lasts about 176 Earth days.
  • Astronomers believe that a 100 km wide asteroid hit Mercury about 4 billion years ago, creating a crater 1,545 km wide. This crater, called the Caloris Basin, is so large that the state of Texas would fit inside it.
  • Mercury travels around the Sun at about 180,000 kph. This is about 73,000 kph faster than Earth's orbital speed.


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