Earth is the third planet from the Sun, and the densest and fifth-largest of the eight planets in the Solar System. It is also the largest of the Solar System's four terrestrial planets. It is sometimes referred to as the world, the Blue Planet, or by its Latin name, Terra. Earth formed approximately 4.54 billion years ago by accretion from the solar nebula, and life appeared on its surface within one billion years.
The sun, planets and Voyager probes sit inside the tiny yellow dot at right, within a giant sphere called the Oort cloud. This reservoir of trillions of ice chunks extends 100,000 astronomical units out, tethered to the sun by gravity. Astronomers believe these objects got thrown out of the inner solar system as the planets took shape 4.5 billion years ago.