Betelgeuse shrinks.

Betelgeuse, one of the brightest stars visible to the naked eye, has shrunk in diameter by more than 15 percent since 1993. The star, a red supergiant, has a radius roughly the distance between the sun and Jupiter. The shrinkage corresponds to contracting by a distance equal to that between the sun and Venus, researchers reported June 9. It's unclear why Betelgeuse has shrunk and whether it will later rebound, said Nobel laureate Charles Townes, retired from the University of California, Berkeley. Townes and Edward Wishnow, also of UC Berkeley, used an infrared interferometer atop Mount Wilson in southern California to examine the star at a wavelength of 11.1 micrometers, which can penetrate the star's outer gas and dust to determine its visible edge.