CONSTELLATIONS Constellations are groupings of the brighter visible stars in the night sky. Many of these groupings are based on imaginary figures that are seen on the inner surface of a huge sphere surrounding the earth. They divide the celestial sphere into 88 constellations, 47 of which date from ancient times and were listed by the astronomer Ptolemy. The boundaries are often complex. But all segments of the boundaries lie ease-west and north-south on the celestial sphere. …showed first 75 words of 601 total…

…showed last 75 words of 601 total…named in Antares, meaning "rival to Mars," probably because the planet has a similar red hue. It is estimated to be 400 times the diameter of the sun and 9,000 times more luminous. About halfway down the scorpion's tail lies a region sometimes called the Table of Scorpius, which is unusually rich in stellar objects. The double stars Zeta Scorpii 1 and 2 can be identified with the unaided eye in the table. The scorpions stinger is called Shaula.