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 |
|---|---|
| Twilight |
The period before sunrise and after sunset when the sky is partially illuminated by scattered sunlight. Civil twilight is defined as the period when the zenith distance of the centre of the Sun's disc is between 90° 50' and 96°; nautical twilight is the interval when it is between 96° and 102°, and astronomical twilight that when it is between 102° and 108°.
|