Mass Extinction And The Structure Of The Milky Way
Authors:
1. M. D. Filipović (a)
2. J. Horner (b,c)
3. E. J. Crawford (a)
4. N. F. H. Tothill (a)
Affiliations:
a. University of Western Sydney, Locked Bag 1797, Penrith South DC, NSW 1797, Australia
b. School of Physics, University of New South Wales, Sydney 2052, Australia
c. Australian Centre for Astrobiology, University of New South Wales, Sydney 2052, Australia
Abstract:
We use the most up to date Milky Way model and solar orbit data in order to test the hypothesis that the Sun's galactic spiral arm crossings cause mass extinction events on Earth. To do this, we created a new model of the Milky Way's spiral arms by combining a large quantity of data from several surveys. We then combined this model with a recently derived solution for the solar orbit to determine the timing of the Sun's historical passages through the Galaxy's spiral arms. Our new model was designed with a symmetrical appearance, with the major alteration being the addition of a spur at the far side of the Galaxy. A correlation was found between the times at which the Sun crosses the spiral arms and six known mass extinction events. Furthermore, we identify five additional historical mass extinction events that might be explained by the motion of the Sun around our Galaxy. These five additional significant drops in marine genera that we find include significant reductions in diversity at 415, 322, 300, 145 and 33 Myr ago. Our simulations indicate that the Sun has spent ~60% of its time passing through our Galaxy's various spiral arms. Also, we briefly discuss and combine previous work on the Galactic Habitable Zone with the new Milky Way model.
The problem with periodicity is the extinctions in question often have wildly disparate basal causes. Periodicity requires a single driver which is extraterrestrial in nature. Exceedingly few of these look like that is even a remote possibility: especially the Eocene.
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