Astronomers Able, for First Time, to Watch as a Comet Explodes

Comet Linear, which exploded in a fiery burst on July 26, shortly after its passage around the sun, is now a cluster of small icy bodies called cometesimals, according to new images captured by the Hubble Space Telescope and the European Southern Observatory in Paranal, Chile. Linear was barely visible to the naked eye before it flashed into brightness, then disappeared. The photo above shows that the comet--technically known as C/1999 S4--has broken up into at least 20 major pieces, each with its own small tail. Though comets have been known to break up after passing close to the sun, this is the first time astronomers have been able to watch the process. Because the picture is a time exposure, images of stars are seen as long tails.

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--Compiled by Times medical writer Thomas H. Maugh II