Post by Chicago Astronomer - Astro Joe on Jun 15, 2005 22:37:25 GMT -6
Are Meteor Showers Misunderstood?
NASA's Deep Impact mission is about to smash into comet 9P/Tempel 1 to excavate a crater and probe the comet's internal structure. It's possible, however, that the comet will break into fragments, creating a cloud of meteoroids. That, say astronomers, may not be unnatural.
"If comet 9P/Tempel 1 breaks during NASA's Deep Impact mission on July 4, a meteoroid stream will be created in much the same manner as the mechanism that causes most of our meteor showers," according to SETI Institute astronomer Dr. Peter Jenniskens in a paper accepted for publication in the Astronomical Journal.
"The 19th century idea that meteor showers originate from the breakup of comets went into remission after astronomer Fred Whipple, in 1951, developed a quantitative description of meteoroid acceleration by the drag of water vapor," says Jenniskens. "Ever since, meteor showers were thought to be caused by the gradual ejection of meteoroids when the comet's ices evaporated on approach to the Sun."
Instead, it now appears that many meteoroid streams are caused by wholesale disintegration of comets, which are loose assemblages of cometesimals and are known to frequently break apart. There are several possible causes of such fragmentations, one of which is collisions with large meteoroids such as simulated in the Deep Impact mission.
More here: www.spaceref.com/news/viewpr.html?pid=17136
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Let's see if this creates a good size meteor shower.