May 18, 2001. Copyright 2001. Graphic News. All rights reserved.

Story goes with pictures GN12433 and GN12434.

Picture shows remains of the nucleus of Comet LINEAR after it disintegrated in space, leaving behind tiny particles spread out over 62,000 miles (100,000 km) as well as 16 big chunks up to 330 feet (100 metres) across.
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Hubble discovers missing pieces of Comet LINEAR 

LONDON, May 18, Graphic News: To the surprise and delight of astronomers, NASAÕs Hubble Space Telescope has discovered a small armada of Òmini-cometsÓ left behind from what some astronomers had prematurely thought was a total disintegration of the Comet LINEAR. 

In one observation HubbleÕs powerful vision has settled the fate of the mysteriously vanished nucleus of the comet -- the Òdirty snowballÓ made up of frozen water and other ice and bits of rock and dust. The partial disintegration of the cometÕs icy heart is reported in the current edition of the journal Science.

LINEAR was reported Òmissing in actionÓ following its passage around the Sun last year on July 26. The comet disintegrated in space, leaving behind tiny particles spread out over 62,000 miles (100,000 km) as well as 16 big chunks up to 330 feet (100 metres) across.

Though comets have been known to break apart and vanish before, for the first time astronomers are getting a close-up view of the dismantling of a cometÕs nucleus due to warming by the Sun. The results support the popular theory that comet nuclei are really made up of a cluster of smaller icy bodies called Òcometesimals.Ó

On July 27, ground-based observers had lost sight of the bright core of the comet and were suggesting that the nucleus had totally disintegrated into a pile of dust. Astronomers at the Space Telescope Science Institute (STScI) in Baltimore, Md., quickly reprogrammed Hubble to go looking for the AWOL nucleus. Not expecting to see much, Johns Hopkins University astronomer Harold Weaver was stunned when the Hubble picture popped up on his computer screen. ÒMy first thought was Hubble Space Telescope does it again! We caught the fish! This is amazing, very exciting, very neat.Ó

ÒIÕve never seen another comet behave this way,Ó Weaver said. ÒIt was a puzzle as to why it came apart so dramatically -- I have never seen a comet nucleus that has come apart [and] seemed to disappear.Ó

Astronomers study comets because they are believed to be some of the remnants of the formation of the solar system, and may offer evidence about how the sun, planets and other features came to be.

The death of LINEAR was especially interesting, Weaver said because scientists may be able to look at the cometÕs demise as they would a movie running backward, to reconstruct what may have happened at the solar systemÕs birth.

LINEAR seemed to break apart in stages, which suggests that heating by the sun did not make it explode. Instead, Weaver said, the comet may have died due to fast rotation, smashups with asteroid debris or a combination of the two.

Comets are some of the most primitive bodies in the solar system, and LINEAR is believed to date back an estimated 4.6 billion years. It was first spied in 1999 when it was heading toward the Sun from a region out by Jupiter and Saturn.
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Sources: Space Telescope Science Institute, Johns Hopkins University, Baltimore, Reuters