Astronomy Dictionary

Browse through Sky at Night Magazine’s comprehensive astronomical dictionary, with over 300 entries.


The point on the celestial sphere that is directly above an observer.

Zenithal hourly rate (ZHR)

The number of meteors during a meteor shower that an observer at a dark site would see during the course of an hour with the radiant overhead.


Constellations that the Sun, Moon and major planets appear to pass through as the Earth moves along its orbit.

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