It's certainly happened in the past, and not so long ago. What worries me is the Yellowstone caldera, which is just itching to bury the West (again) deep in ash. --- On Thu, 7/23/09, Chuck Hards <chuck.hards@gmail.com> wrote: From: Chuck Hards <chuck.hards@gmail.com> Subject: Re: [Utah-astronomy] Asteroid or Comet Collision With Earth Probability To: "Utah Astronomy" <utah-astronomy@mailman.xmission.com> Date: Thursday, July 23, 2009, 6:21 PM BTW, for the worriers among us, some scientists feel that the earth is overdue for a "nuclear" sized impact; one big enough to cause major disruptions or even mass extinction.  Thus the current emphasis on finding and cataloging objects that cross earth's orbit.  (Get busy, Patrick!) ;o) Combat soldiers are fond of saying that you never hear the one (bullet) that gets you... _______________________________________________ Utah-Astronomy mailing list Utah-Astronomy@mailman.xmission.com http://mailman.xmission.com/cgi-bin/mailman/listinfo/utah-astronomy Visit the Photo Gallery: http://www.slas.us/gallery2/main.php Visit the Wiki: http://www.utahastronomy.com