Who believes this?
I'm pretty sure we would have noticed it sooner.
10,000 to 20,000 year to make 1 orbit doesn't sound realistic either.
http://www.cnn.com/2016/01/20/us/possible-ninth-planet/index.html
I'm pretty sure we would have noticed it sooner.
10,000 to 20,000 year to make 1 orbit doesn't sound realistic either.
http://www.cnn.com/2016/01/20/us/possible-ninth-planet/index.html