Glossary of Observational Astronomy
Check the Munich Astro Archive
Glossary.
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- Astronomical Twilight
- When the position of the Sun is below the horizon and between 12 and 18 degrees below the
horizon.
- Meridian
- A reference line in the sky that passes thorugh the celestial poles and zenith.
For locations in the northern hemisphere the meridian passes very close to the star Polaris since Polaris is within one degree of the north celestrial pole.
- Polaris
- The brightest star within one degree of the north celestrial pole.
Used to establish the North direction reference.
Sometimes refered to as the North Pole star.
Located in the constellation
Ursa Minor
- Zenith
- A reference point in the sky that is directly over head.
© 1998-2006 David Haworth
