Famous Star Is Shrinking, Puzzling Astronomers

A Hubble Space Telescope image taken in 1996 shows the red supergiant star Betelgeuse, one of the brightest stars in the familiar constellation Orion.Betelgeuse, one of the largest known stars, is shrinking rapidly and no one knows why, astronomers said at a June 2009 meeting. Image courtesy A. Dupree (CfA), R. Gilliland (STScI), NASA

From The National Geographic:

One of the largest known stars in the universe is shrinking rapidly, and astronomers don't know why.

Betelgeuse (pronounced almost like "beetle juice") is a red supergiant star 600 light-years away in the constellation Orion. From Earth the star is clearly visible with the naked eye as the reddish dot that marks Orion's left shoulder.

Researchers at the University of California, Berkeley, first measured the star in 1993 with an infrared instrument on top of Southern California's Mount Wilson. They estimated the star to be as big around as Jupiter's orbit around the sun.

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