|Round we go.|
Tuesday, 7 July 2015
Deadly thing with 200 million year orbit keeps blasting Earth with death?
The great and minor extinctions in our fossil record have a bit of a rhythm near the 195 million year mark and another in the 26-35 million year range. David Brin speculated in 1984 that the periodical encounter with a galactic shock wave or a ray-spewing black hole orbiting a little quicker than Earth's 240 million year track around the galaxy could explain this. The math isn't much different than the calculations for earth-moon interactions. If it exists, it is about 2.4 kilo-parsecs out from the galaxy core while earth sits at 10. All this is in addition to meteor mashups. A periodic particle flux can collapse Earth's ecosystem. What a beautiful idea on a cosmic scale!
The author, David Brin, links to an update to this speculation which involves dark matter and the thoughts of NYU's Michael Rampino.