Kim recently was brave enough to take on a common misconception about the concept of what is normal. More of this needs to be done and I hope that no one becomes offended. I would like to address the concept that the earth is "due" for a Tunguska size impact event. Frontrunner train arrivals can be considered to be "due" because each train is part of a coordinated system of schedules and operators communicating with a central dispatcher who keeps things running as expected. Impact events are not subject to a dispatcher with a schedule to keep, they are independent events. Let's assume that the odds of getting hit are once every 100 years. Then the olds of a hit during any one year are 1 in 100. That is true for all years; the year before Tunguska, the year after Tunguska, the year OF Tunguska, and this year, more than a century after Tunguska. The odds on each year are the same: 1 in 100. That's the way statistical odds work for unrelated events. In a coin flip example, if you happen to toss heads three times in a row the odds of doing so on the next flip is 50%. If you manage to toss 10 consecutive heads in a row, the odds on the next flip are still 50%. That's because the coin is just a lump of metal without any memory of recent events or expectations of future events. So as far as Tunguska is concerned, you should go out and buy a bunch of green bananas with the full confidence that you have plenty of time for them to ripen. Impact events are never "due". DT --- 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, 5:21 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