Friday, March 7, 2008
Lyra (the Harp) is a small but important norterm constellation located between Hercules and Cygnus. Its brightest star, Vega (magnitude 0.04), is the fifth brightest in the heavens. Located 26 light-years from the Sun, Vega will be the pole star in about 12,000 years because of the precession of the Earth's axis. The second-brightest star, Sheliak (from the Arabic al-shlyad, meaning "harp"), is an eclipsing binary. Another object in the constellation, Epsilon lyrae, is resolvable, with keen eyesight or binocular, into two stars; a telescope reveals that each of them in turn is double. Other important objects include the Ring Nebula in Lyra (M 57, or NGC 6720) a planetary nebula shaped like an elliptical smoke ring, and the prototype RR Lyrae variable star.