View of the Earth as seen by the Apollo 17 crew traveling toward the Moon. This translunar coast photograph extends from the Mediterranean Sea area to the Antarctica south polar ice cap. This is toward the northeast. Earth, also known as Terra, and (mostly in the 19th century) Tellus, 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 years ago, and shortly thereafter (4.533 billion years ago) acquired its single natural satellite, the Moon.