Abstract
Astronomical and geological evidence is consistent with the hypothesis that mass extinctions of life on Earth are related to impacts of comets whose flux is partly modulated by the dynamics of the Milky Way Galaxy. Geologic evidence for impact (ejecta and large impact craters) has been found at times of mass extinction events, and the record of large dated craters shows a significant correlation with extinctions. Statistical analyses suggest that mass extinction events exhibit a periodic component of about 30 Myr, and periodicities of 30 ± 0.5 Myr and 35 ± 2 Myr have been extracted from sets of well-dated large impact craters. These results suggest periodic or quasi-periodic showers of impactors, probably Oort Cloud comets, with an approximately 30 or 36 Myr cycle. The best explanation for these proposed quasi-periodic comet showers involves the Sun's vertical oscillation through the galactic disk, which may have a similar cycle time between crossings of the galactic plane. Further refinement of the model will depend on the identification and quantification of the dark matter component in the galactic disk, and discovery and accurate dating of additional impact craters.
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Disclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.