Earth seems to fill the sky in this image taken by the crew of Apollo 17 in 1972. The picture marked the first time astronauts were able to photograph the south polar ice cap.
Planet Earth, explained
Our home planet provides us with life and protects us from space.
Earth, our home planet, is a world unlike any other. The third planet from the sun, Earth is the only place in the known universe confirmed to host life.
With a radius of 3,959 miles, Earth is the fifth largest planet in our solar system, and it's the only one known for sure to have liquid water on its surface. Earth is also unique in terms of monikers. Every other solar system planet was named for a Greek or Roman deity, but for at least a thousand years, some cultures have described our world using the Germanic word “earth,” which means simply “the ground.”
Earth orbits the sun once every 365.25 days. Since our calendar years have only 365 days, we add