12900 years ago an extinction occurred to great mammals of northern hemisphere. There has been other great ice ages in earths history and these mammals survived. This extinction was different and occured during the waneing part of our last great ice age 14000 years ago. At 12900 years ago all these animals went extinct. No smoking gun could be found. It is now belived a large comet struck the northern hemisphere and iridium confirms a strike but how do you find the crater. NASA Ames institude in San Franciso did some research of many impact sites and in all the sites core samples carbon spherial globules were found in every sample. A scientist cracked these sphereical carbon capsules contained several types of diamond both crystaline and hexagonal diamonds were found. Hexigonal diamonds are only found in space and impact sites and cosmic dust. These diamonds are nano-diamonds a 100000 would fit into a grain of sand. The exciting thing else to test their theory they went to greenland trying to find a time-line in the greenland ice sheet and their very first sample at the 12900 years had the nano-diamonds in the sample. Now a confirming time line can be made in favor of a comet hitting the large icesheet and the ice acted like a kelvar vest and cracked and shattered melted and disappeared with not much cratering to be observed. By reference to the greenland ice sheet alot is recorded back more than 450000 years of its existance. The discovery is simular to a Mona Lisa experiance to the discoverers.

Nasa also plotted an earth crossing meteor and predicted its impact in Sudan. Lo and behold the carbon speroids found in the fragments contain nano-diamonds in every sample collected from the meteor. This is the first meteor plotting as earth crossing asteroid and followed to its impact site where over 25 pounds of meteor samples found.

Based on what we have good reason to think we know of comets, it seems an extremely remote possibility that one crashed into Earth as recently as 12,900 years ago. It's rather like a tossed coin landing on edge and staying there, after, say, ten tosses, but even much more so. Michael

Comets crash into the sun many times a year go goggle SOHO that satilitte has found over 2000 comets and 98% arent seen by the earth. These things just flash into the sun outta no where completely unseen..Until they get close enought for SOHO to see the comets death dive. Many comets are asteriod once their gasses vapourize away and you have a rocky remnant left.

'The rate of long period comet impacts (on Earth) is on the order of one every 32 million years, whereas the rate of comparably-sized asteroid impacts is more like once every 500,000 years.' -- Daniel Durda, a senior research scientist, Southwest Research Institute, Boulder Colorado (quoted in article: Comets: How big a threat to Earth? on: http://news.nationalgeographic.com. The *very much* greater gravitational field of the Sun, compared to that of the Earth undoubtedly explains why it is able to attract so many more comets to itself. Michael