Space exploration began with the launch of Sputnik and Astrophysics was born as the application of physics to the phenomena observed by Astronomy, which etymologically means laws of the stars.
There are 2759 entries in this glossary.| Term | Definition |
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| Universe |
The entirety of all that exists. The size of the observable universe is limited to the distance light has had time to travel since the Big Bang.
See also: particle horizon.
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