What the heck is Planet Nine, really? (science video).

In this thirty minute science video, the mystery of Panet Nine deepens … as a new theory from Amir Siraj and Avi Loeb of Harvard attempts to explain what exactly might be hiding in the Oort Cloud. A primordial black hole? Or the Sun’s lost twin?

So, was the Sun a binary twin and is that twin actually our Planet Nine?