Astronomy Picture of the Day

Discover the cosmos! Each day a different image or photograph of our fascinating universe is featured, along with a brief explanation written by a professional astronomer.

2000 September 13
See Explanation.  Clicking on the picture will download 
 the highest resolution version available.

Comet LINEAR: Fade To Black
Credit & Copyright: Gordon Garradd

Explanation: Only last month the stage was set for Comet LINEAR (C/1999S4 LINEAR) to become the first "naked-eye" comet of Y2K. It didn't fill that role, of course, but it did turn in a very dramatic performance. Closely followed by astronomer Mark Kidger and colleagues with the Isaac Newton Group telescopes (La Palma, Canary Islands), comet LINEAR's nucleus apparently fragmented extensively on the night of July 25th. A faint fluorescent cloud fading against a background of stars is all that is still visible in this August 21st telescopic view from Loomberah, NSW Australia. Why did comet LINEAR break up? Comets are conglomerates of ice and rock. A very plausible scenario is that a substantial fraction of LINEAR's icy component was evaporated, leaving too little to hold the rocky material together. In any event, no bright telltale condensations remain. So, following its first tour through the inner Solar System, an encore from comet LINEAR seems unlikely!

Tomorrow's picture: Event Horizon

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Authors & editors: Robert Nemiroff (MTU) & Jerry Bonnell (USRA)
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