... and I was only going to check the Astronomy Pic Of the Day this morning. lol

Asteroid or comet triggered death of most species 250 million years ago

***(Interesting article, but I thought this finding was the icing on that cake.)

[For instance, terrestrial helium is mostly helium-4 and contains only a small amount of helium-3, while extraterrestrial helium - the kind found in these fullerenes - is mostly helium-3.

"These things form in carbon stars. That's what's exciting about finding fullerenes as a tracer," Becker said. The extreme temperatures and gas pressures in carbon stars are perhaps the only way extraterrestrial noble gases could be forced inside a fullerene, she said. These gas-laden fullerenes were formed outside the Solar System, and their concentration at the Permian-Triassic boundary means they were delivered by a comet or asteroid.]

http://www.washington.edu/newsroom/news/2001archive/02-01archive/k022201.html

The above made me think of this recent article (pdf in this case): http://acs.pha.jhu.edu/~txitxo/ScoCen.pdf