In 1883, an extinction level 2.5km asteroid may have just missed the Earth. Billion-Ton Comet May Have Missed Earth by a Few Hundred Kilometers in 1883 http://www.technologyreview.com/blog/arxiv/27264/ Did a massive comet almost wipe out humans in 1883? http://tinyurl.com/3z5le5d Interpretation of the observations made in 1883 in Zacatecas (Mexico): A fragmented Comet that nearly hits the Earth http://arxiv.org/abs/1110.2798 Clear Skies - Kurt