so planet 10x Earth, might have an orbit that brings it close to earth every 10-20K years
might be the cause for the "routine" extinction events on earth every 10-20 million years?
wait those number make no sense
planet nine
http://www.space.com/31672-planet-ni...in-images.html
https://www.technologyreview.com/s/4...ark-companion/
The 30-Million-Year Mass Extinction Cycle
http://www.dailygalaxy.com/my_weblog...r-alvarez.html
time for future
https://en.wikipedia.org/wiki/Timeli...the_far_future