Earth (Planet): Earth is the third planet from the Sun and the only object in the Universe known to harbor life. According to radiometric dating and other sources of evidence, Earth formed over 4 billion years ago.

Earth (Planet): Earth, otherwise known as the World or the Globe, is the third planet from the Sun and the only object in the Universe known to harbor life. It is the densest planet in the Solar System and the largest of the four terrestrial planets. According to radiometric dating and other sources of evidence, Earth formed about 4.54 billion years ago.