The sun forms within a cloud of gas in a spiral arm of the Milky Way Galaxy. A vast disk of gas and debris that swirls around this new star gives birth to planets, moons, and asteroids . Earth is the third planet out.

The image on the left, from the Hubble Space Telescope, shows a newborn star in the Orion Nebula surrounded by a disk of dust and gas that may one day collapse into planets, moons and asteroids.