The Inner Planets are the four closest planets to the Sun. They are Mercury, Venus, Earth and Mars! Here are some FUN FACTS about the Inner Planets!


  • Mercury is about the same size as our Moon.
  • Mercury can be one of the hottest, or coldest planets in our solar system. From day to night, the temperature on Mercury can drop 1,080° Fahrenheit!!!
  • Mercury is the fastest planet in our solar system. It travels around the sun going 107,000 miles per hour!
  • On most clear nights, you can see the planet Mercury just before sunrise, or just after sunset.


  • Venus is considered to be the Earth's twin. This is because, in our solar system, they are the two planets that are closest together, and they are about the same size!!
  • Venus is the brightest planet in the Earth's sky. In other words, if you were to look up at the sky at night, Venus would be the easiest planet to see. Because of this, Venus is often called "The Evening Star"
  • Venus is the hottest planet in the solar system, even though it is NOT the closest planet to the Sun!!
  • When Venus is facing the Sun, the temperature of Venus can reach 903.2° Fahrenheit!


  • The Earth is about 4.6 billion years old!! (That's as old as the Sun!)
  • The Earth is about 93.2 million miles from the Sun.
  • 70% of the Earth's surface is covered in water. It is the only inner planet that has liquid water on its surface!
  • The Earth does not lay straight up and done in the solar system. Instead, the Earth's axis is tilted. Because of this tilt, we are able to have four seasons. If the Earth was not tilted, the temperature would be the same all year round!


  • Mars has a lot less gravity than the planet Earth. If you were to go to Mars, you would even be able to play basketball!
  • If you weighed 100 pounds on Earth, you would opnly weigh 38 pounds on Mars!
  • A year on Mars is about the same as TWO years on Earth! (one year on Mars is 687 Earth days)
  • The month of March was named after the planet Mars.