Overview of and topical guide to Earth
The followingoutline is provided as an overview of and topical guide to the planet Earth:
Earth – third planet from theSun, the densest planet in theSolar System, the largest of the Solar System's fourterrestrial planets, and the onlyastronomical object known to harborlife.
Classification of Earth
[edit]Earth's location in the Universe
- 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 (110 million light-years), 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
Movement of the Earth
[edit]This sphere represents all water on Earth, wherever it is and in whatever form within thewater cycle.
- Water, by relative altitude
Water, by salt content
[edit]Astronomical events on Earth
[edit]Natural satellites of Earth
[edit]History of Earth
Future of Earth
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