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News Release 659 of 1051

May 17, 2001 02:00 PM (EDT)

News Release Number: STScI-2001-14

Astronomers Puzzled over Comet LINEAR's Missing Pieces

May 17, 2001: Astronomers analyzing debris from a comet that broke apart last summer spied pieces as small as smoke-sized particles and as large as football-field-sized fragments. But it's the material they didn't see that has aroused their curiosity. Tracking the doomed comet, named LINEAR, the Hubble telescope and the Very Large Telescope in Chile found tiny particles that made up the 62,000-mile-long dust tail and 16 large fragments, some as wide as 330 feet. But the telescopes didn't detect any intermediate-sized pieces. If they exist, then the fundamental building blocks that comprised LINEAR's nucleus may be somewhat smaller than current theories suggest.

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Q & A: Understanding the Discovery

  1. 1. How do astronomers know that pieces are missing?

  2. Astronomers compared the estimated mass of comet LINEAR's nucleus before it disintegrated with the estimated mass of the debris spied last summer by Hubble and the Very Large Telescope. The two numbers didn't match up. In fact, the mass of the debris was 100 times less than the mass of the intact nucleus.

  3. 2. Where are the missing pieces?

  4. Astronomers suggest that most of the comet's bulk after the breakup was contained in pebble-sized to house-sized fragments. These fragments cannot be seen by visible-light telescopes because they do not have enough surface area to make them stand out in reflected sunlight.

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Credit: NASA and Hal Weaver (The Johns Hopkins University, Baltimore, MD)