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The left-most picture here was taken by a ground-based telescope run by the University of Hawaii. In this image, Comet Linear appears as a diffuse, elongated cloud of debris without any visible nucleus. The image on the right was taken by the Hubble Space Telescope on the same day, August 5, 2000. Hubble's resolution was needed to show that the nucleus of the comet had actually fragmented into many pieces. Scientists call these leftover pieces "cometesimals". Hubble has found at least 16 of these "cometesimals", some of which are as wide as 330 feet across.
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NASA, Harold Weaver (Johns Hopkins University), and the HST Comet LINEAR Investigation Team

The Amazing, Vanishing Linear!
News story originally written on May 25, 2001

Comet Linear was discovered on September, 27, 1999, by the Lincoln Near-Earth Asteroid Research program.

Astronomers thought LINEAR would not be as spectacular as other recent comets like Hyakutake and Hale-Bopp. After all, it was much dimmer than these comets. But, LINEAR did put on a tremendous show for the Hubble Space Telescope. The Hubble was tracking the comet for two days, July 5-7, 2000. On July 5, 2000, comet Linear blew off a piece of its crust. The Hubble telescope watched the light brighten by an extra 50% in less than four hours. The eruption threw off a great deal of dust into space. Then, when comet Linear came closest to the Sun on July 26, 2000 (still 114 million kilometers away though!), the comet nucleus broke apart! Now comet Linear is little more than a trail of debris orbiting the Sun.

Astronomers have been studying the comet since last summer when it broke apart. Using a variety of telescopes, astronomers have seen leftover pieces of Linear as small as a smoke particle and as big as a football field! But it's the material astronomers don't see that remains a mystery! Astronomers haven't found the intermediate-sized pieces of the comet that would confirm theories as to how big the nucleus of Linear was before it broke apart. In other words, researchers have found there is not as much material in the fragments as there was in Linear before it broke apart. The leftover material just wouldn't add up to a comet as large as Linear. Further studies of debris left by this comet may change what scientists think of comet Linear's nucleus and comet structure in general.

Last modified May 23, 2001 by Jennifer Bergman.

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Windows to the Universe, a project of the National Earth Science Teachers Association, is sponsored in part is sponsored in part through grants from federal agencies (NASA and NOAA), and partnerships with affiliated organizations, including the American Geophysical Union, the Howard Hughes Medical Institute, the Earth System Information Partnership, the American Meteorological Society, the National Center for Science Education, and TERC. The American Geophysical Union and the American Geosciences Institute are Windows to the Universe Founding Partners. NESTA welcomes new Institutional Affiliates in support of our ongoing programs, as well as collaborations on new projects. Contact NESTA for more information. NASA ESIP NCSE HHMI AGU AGI AMS NOAA