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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| Ephemeris Time Et |
The time used prior to 1984 in calculations involving gravitational theories of the solar system. In 1984 it was replaced by dynamical time.
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