Gentlefolk, I grabbed a graph off the web << http://www.au.af.mil/au/2025/volume3/chap16/v3c16-1.htm#The Threat>> and traced it in ASCII below. If I believe it, a Tunguska-sized body should actually hit us every century or so, about a 1% chance each year. At a miss distance of rmin = 120,000 km, the cross sectional area of the Earth vs the area of a circle that size is (rE/rmin)^2 = (6378/120000)^2 = .002825, about a quarter of 1 percent. From this I infer that we may miss seeing about 3 of these for every one we see. --Best, Gerald
(note:view this in a non-proportional font. All the x's on the left should line up) Size(m) 3 10 30 100 300 1k 3k 10k Monthly xx Yearly xxxxxx Decade xxxxxxxxxx Century xxxxxxxxxxxxxx (Tunguska) 1ka xxxxxxxxxxxxxxxxxx 10 ka xxxxxxxxxxxxxxxxxxxxxx (Barringer) 100 ka xxxxxxxxxxxxxxxxxxxxxxxxxx 1Ma xxxxxxxxxxxxxxxxxxxxxxxxxxxxxx 10 Ma xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx 100 Ma xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx(KT) 1Ga xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx _______________________________________________ ERPS-list mailing list [EMAIL PROTECTED] http://lists.erps.org/mailman/listinfo/erps-list
