Sun's Movement Through Milky Way Regularly Sends Comets Hurtling, Coinciding With Mass Life ExtinctionsA large body of scientific evidence now exists that support the hypothesis that a major asteroid or comet impact occurred in the Caribbean region at the boundary of the Cretaceous and Tertiary periods in Earth's geologic history. Such an impact is suspected to be responsible for the mass extinction of many floral and faunal species, including the large dinosaurs, that marked the end of the Cretaceous period. (Credit: Art by Don Davis / Courtesy of NASA) ScienceDaily (May 2, 2008) — The sun's movement through the Milky...