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 ...

Learn all about the planets in the solar system and their order from the Sun. Learn about the force of gravity that pulls all objects towards the Earth. Day and night Learn how day and night ...

Earth formed over 4.5 billion years ago from a swirling cloud of gas and dust squished together by gravity. That same cloud gave rise to our entire solar system, including our star, the sun.