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Betelgeuse shrinks

The red supergiant has lost 15 percent of its size

PASADENA, Calif. — Betelgeuse, one of the brightest stars visible to the naked eye, has shrunk in diameter by more than 15 percent since 1993.

SHRINKING GIANT This ultraviolet image of the red supergiant star Betelgeuse was taken in 1996 with the Hubble Space Telescope. New infrared observations with a ground-based interferometer now reveal that the star's diameter has mysteriously shrunk by more than 15 percent over the past 15 years. ~~ Andrea Dupree/Harvard-Smithsonian CfA, Ronald Gilliland/STScI, NASA, ESA

STAR TRACKER Physicist Charles Townes cleans one of the mirrors of the infrared spatial interferometer that he and colleagues have used to monitor Betelgeuse since 1993. ~~ C. Ryan