Wikipedia:Today's featured article/November 26, 2012
Betelgeuse is the eighth-brightest star in the night sky and second-brightest in the constellation of Orion, only rarely outshining Rigel. It is a distinctly reddish, semiregular variable star whose apparent magnitude varies between 0.2 and 1.2, the widest range of any first-magnitude star. Betelgeuse's name is thought to be derived from the Arabic يد الجوزاء Yad al-Jauzā' meaning "the Hand of al-Jauzā'", i.e., Orion. It is classified as a red supergiant of spectral type M2Iab and is one of the largest and most luminous known stars. If positioned at the center of the Solar System, its surface would extend past the asteroid belt, possibly beyond the orbit of Jupiter, at least wholly engulfing Mercury, Venus, Earth and Mars. Less than 10 million years old, Betelgeuse has evolved rapidly due to its high mass. Ejected from its birthplace in the Orion OB1 Association, this crimson runaway has been observed moving through the interstellar medium supersonically at a speed of 30 km/sec, creating a bow shock over 4 light-years wide. Now in a late stage of stellar evolution, the supergiant is expected to proceed through its life cycle before exploding as a type II supernova within the next million years. (Full article...)
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