Anatomy of a Busted Comet Date: 1 Feb 2008 NASA's Spitzer Space
Telescope captured the picture on the left of comet Holmes in
February 2008, four months after the comet suddenly erupted and
brightened a millionfold overnight. The contrast of the picture
has been enhanced on the right to show the anatomy of the comet.
Every six years, comet 17P/Holmes speeds away from Jupiter and
heads inward toward the sun, traveling the same route typically
without incident. However, twice in the last 116 years, in
November 1892 and October 2007, comet Holmes mysteriously
exploded as it approached the asteroid belt. Astronomers still
do not know the cause of these eruptions. Spitzer's infrared
picture at left reveals fine dust particles that make up the
outer shell, or coma, of the comet. The nucleus of the comet is
within the bright whitish spot in the center, while the yellow
area shows solid particles that were blown from the comet in the
explosion. The comet is headed away from the sun, which lies
beyond the right-hand s