How Do Astronomers Locate Stars On a Celestial Globe Using Declination and Right Ascension?

A celestial globe is marked with imaginary vertical and horizontal lines called declination (dec) and right ascension (RA).

These lines correspond to latitude and longitude lines on a terrestrial globe.

Just as you can locate a town by finding the intersection of its latitude and longitude, Sonora, Texas, sits approximately at 30° north latitude and 100° west longitude, you can find a star at the intersection of its declination and right ascension.

The star Arcturus is at 14 hours, 15 minutes, 40 seconds RA, 19°11′ north (or +19°11′) dec.

In the Aristotelic and Ptolemaic models, the celestial sphere was imagined as a physical reality rather than a geometrical projection.

A celestial globe is also known as an armillary sphere.

About Karen Hill

Karen Hill is a freelance writer, editor, and columnist. Born in New York, her work has appeared in the Examiner, Yahoo News, Buzzfeed, among others.

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