Crashing comets not likely the cause of Earth's mass extinctions


	Crashing comets not likely the cause of Earth's mass extinctions

tabsey

8-4-2009 7:01 AM

78 views

tags:

space, extinction

tabsey says:

Saturn and Jupiter to the rescue, as may have been the case recently.

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<div style="margin: 12px 0px; font-family: arial; color: #333333; background: #ffffff; border: solid 4px #e5e5e5; width: 100%; clear: left;"><div class="CM_CTB_Content_Wrap" style="margin: 0px; padding: 0px;background-color: #ffffff;"><div style="border-bottom: solid 1px #dcdcdc; white-space: nowrap; margin-bottom: 8px; background-color: #eeeeee ;background-image: url(http://clipmarks.com/images/source-bg.gif); background-repeat: repeat-x; height: 24px; line-height: 24px; vertical-align: middle; padding-bottom: 4px; color: #666666; font-size: 10px;" ><a href="http://clipmarks.com/clip-to-blog/" title="see clips that are hot right now"><img src="http://content.clipmarks.com/blog_embed/4d0fd307-88fa-42bb-aad7-70e5ef8793dc/5D52AACB-795B-4CE9-9F04-54053ECE2EFE/" alt="" width="19" height="19" border="0" style="vertical-align: middle; margin: 0px 4px; display: inline; border: none; float:none;" /></a>clipped from <a title="http://www.astronomy.com/asy/default.aspx?c=a&id=8502" href="http://www.astronomy.com/asy/default.aspx?c=a&id=8502" style="font-size: 11px;">www.astronomy.com</a></div><blockquote style="text-align: left; padding: 0px 8px; margin: 4px 0px 8px 0px; background: transparent; border: none;" cite="http://www.astronomy.com/asy/default.aspx?c=a&id=8502"><DIV>Scientists have debated how many mass extinction events in Earth's history a space body crashing into the planet's surface has triggered. Most agree that an asteroid collision 65 million years ago brought an end to the age of dinosaurs, but there is uncertainty about how many other extinctions might have resulted from asteroid or comet collisions with Earth.</DIV></blockquote><div style="height: 2px; font-size: 2px; background: #dcdcdc; border-bottom: solid 1px #f5f5f5; margin: 2px 4px;"></div><blockquote style="text-align: left; padding: 0px 8px; margin: 4px 0px 8px 0px; background: transparent; border: none;" cite="http://www.astronomy.com/asy/default.aspx?c=a&id=8502"><DIV>In fact, astronomers know the inner solar system has been protected at least to some degree by Saturn and Jupiter, whose gravitational fields can eject comets into interstellar space or send them crashing into the giant planets. That point was reinforced July 20 when a huge scar appeared on Jupiter's surface, likely evidence of a comet impact.</DIV></blockquote><div style="height: 2px; font-size: 2px; background: #dcdcdc; border-bottom: solid 1px #f5f5f5; margin: 2px 4px;"></div><blockquote style="text-align: left; padding: 0px 8px; margin: 4px 0px 8px 0px; background: transparent; border: none;" cite="http://www.astronomy.com/asy/default.aspx?c=a&id=8502">New University of Washington research indicates it is highly unlikely that comets have caused any mass extinction or have been responsible for more than one minor extinction event</blockquote></div><div style="margin: 0px 6px 6px 4px;"><table style="font-size: 11px;border-spacing: 0px;padding: 0px;" cellpadding="0" cellspacing="0" width="100%"><tr><td style="background:transparent;border-width:0px;padding:0px;">&nbsp;</td><td align="right" style="background:transparent;border-width:0px;padding:0px;width:107px" width="107"><a href="http://clipmarks.com/share/5D52AACB-795B-4CE9-9F04-54053ECE2EFE/blog/" title="blog or email this clip"><img src="http://content8.clipmarks.com/images/c2b-foot.png" border="0" alt="blog it" width="107" height="17" style="border-width:0px;padding:0px;margin:0px;" /></a></td></tr></table></div></div>

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