|the fainter of the two stars that constitute a double or binary star|
|the obscuring of the light of the moon by the intervention of the earth between it and the sun, a lunar eclipse, or the obscuring of the light of the sun by the intervention of the moon between it and a point on the earth, a solar eclipse|
|supergiant (s'pər-jī'ənt) Pronunciation Key
A star that is larger, brighter, and more massive than a giant star, being thousands of times brighter than the Sun and having a relatively short lifespan—only about 10 to 50 million years as opposed to around 5 billion years for the Sun. Supergiants, such as Betelgeuse and Rigel in Orion, are only found in young cosmic structures such as the arms of spiral galaxies. Red supergiants such as Betelgeuse are late-stage stars, having burned most of their hydrogen in an earlier stage as main-sequence stars, and now fuse helium into heavier elements through the triple alpha process. Blue supergiants such as Rigel are thought to have evolved from red giants, though some are considered main-sequence stars. Supergiants are thought to eventually undergo a supernova, ending up as neutron stars or black holes.