Outline of Earth

The following outline is provided as an overview of and topical guide to the planet Earth:
Earth - third planet from the Sun, the densest planet in the Solar System, the largest of the Solar System's four terrestrial planets, and the only astronomical object known to harbor life.

Classification of Earth

Universe - all of time and space and its contents.
* Observable universe - spherical region of the Universe comprising all matter that may be observed from Earth at the present time, because light and other signals from these objects have had time to reach Earth since the beginning of the cosmological expansion.
** Laniakea Supercluster – galaxy supercluster that is home to the Milky Way and approximately 100,000 other nearby galaxies. Includes the prior defined local supercluster, the Virgo Supercluster, as an appendage.
*** Virgo Supercluster - one of the approximately 10 million superclusters in the observable universe. It spans 33 megaparsecs, and contains at least 100 galaxy groups and clusters, including the Local Group.
**** Local Group - specific galaxy group that includes the Milky Way and at least 53 other galaxies, most of them dwarf galaxies.
***** Milky Way Galaxy - a specific barred spiral galaxy
****** Orion Arm - a spiral arm of the Milky Way
******* Solar System - the Sun and the objects that orbit it, including eight planets, the third planet closest to the Sun being Earth
******** Earth's orbit - path through which the Earth travels around the Sun. The average distance between the Earth and the Sun is 149.60 million kilometers (92.96 million miles).