The Earth seen from Apollo 17

Earth - The Planets


Earth, also known as Terra, and Tellus mostly in the 19th century, is the third-closest planet to the Sun. It is the largest of the solar system's terrestrial planets, and the only planetary body that modern science confirms as harboring life. Scientific evidence indicates that the planet formed around 4.57 billion (4.57109) years ago, and shortly thereafter (4.533 billion years ago) acquired its single natural satellite, the Moon.