- Cebalrai (stars.astro.illinois.edu)
CEBALRAI (Beta Ophiuchi). At the northern tip of Ophiuchus, the Serpent Bearer, lies Rasalhague, the bright Alpha star. Helping to form the huge rough pentagon that makes the classic figure is Cebalrai, at the pentagon’s northeastern corner, its position and bright third magnitude status (2.77) causing Bayer to call it “Beta.”
- Celestial sphere (Wikipedia)
In astronomy and navigation, the celestial sphere is an abstract sphere that has an arbitrarily large radius and is concentric to Earth. All objects in the sky can be conceived as being projected upon the inner surface of the celestial sphere, which may be centered on Earth or the observer. If centered on the observer, half of the sphere would resemble a hemispherical screen over the observing location.