Summary

Earlier scientists have investigated whether there is any connection between the periodicity of extraterrestrial objects that strike the earth and the periodicity of climate patterns. In the former case, periodic impacts of objects occur separated by 30 to 35 million years. In the latter, scientists have observed both a 20,000-year and a 100,000-year periodic cycle in the earth's climate, Randall notes. Although there are many suggestions for the cause of periodic bombardment of earth with extraterrestrial objects, none of them match with the crater records on earth. Serbian astronomer Milutin Milankovic posited the existence of both a 20,000-year and 1000,000-year periodicity in temperature patterns that reflects global ice ages. These do not serve as evidence of meteoroid strikes on earth, because the search for crater periodicity must take into account much longer time frames spanning millions of years, Randall explains...