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.
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