What is Earth?

Earth is our home planet. Scientists believe Earth and its moon formed around the same time as the rest of the solar system, about 4.5 billion years ago. Earth is the fifth-largest planet in the solar system. Its diameter is about 8,000 miles. And Earth is the third closest planet to the sun. Its average distance from the sun is about 93 million miles. Only Mercury and Venus are closer.

Earth has been called the "Goldilocks planet." In the story of "Goldilocks and the Three Bears," a little girl named Goldilocks liked everything just right. On Earth, everything is just right for life to exist. It's warm, but not too warm. And it has water, but not too much water.