50km is massive. Earth's largest crater[1] is 300km across, and that's thought to have been created by an asteroid 5-10km in diameter. The 180km Chicxulub crat

50km is massive. Earth's largest crater[1] is 300km across, and that's thought to have been created by an asteroid 5-10km in diameter. The 180km Chicxulub crater[2] (this impact is generally believed to be largely responsible for the extinction of dinosaurs) was around 10km in diameter. I'm kind of hoping this turns out to be something. I thought the Russian meteor the other week was a most amazing natural event, and something far bigger than that would be incredible (not to mention safe for humanity in this case). EDIT: 50km is actually the upper estimated limit of the size of this comet. Wikipedia[3] says 8-50km. It's still huge. 1: http://en.wikipedia.org/wiki/Vredefort_crater http://en.wikipedia.org/wiki/Vredefort_crater 2: http://en.wikipedia.org/wiki/Chicxulub_Crater http://en.wikipedia.org/wiki/Chicxulub_Crater 3: http://en.wikipedia.org/wiki/C/2013_A1 http://en.wikipedia.org/wiki/C/2013_A1