NASA believes they found a planet with life on it - aliens - and its almost as if it were Earths twin - Gliese 581G.
According to evidence from radiometric dating and other sources, Earth was formed about 4.54 billion years ago. Earth gravitationally interacts with other objects in space, especially the Sun and the Moon. During one orbit around the Sun, Earth rotates about its own axis 366.26 times, creating 365.26 solar days or one sidereal year. Earths axis of rotation is tilted 23.4° away from the perpendicular of its orbital plane, producing seasonal variations on the planets surface with a period of one tropical year . The Moon is Earths only permanent natural satellite. Its gravitational interaction with Earth causes ocean tides, stabilizes the orientation of Earths rotational axis, and gradually slows Earths rotational rate. (source : wikipedia