Mike Brown: If in 1/2 of the Kuiper belt we find a very smooth distribution of sizes like this, then surveying the other half of the KB it is unlikely we're suddenly going to jump an order of magnitude in size.
(2) There was supposed to be a (2). But I forgot.
Yeah, so Jupiter 2.0 CAN'T live in the Kuiper belt. We've known that for decades simply from watching what the other planets are doing.
Ian O'Neill: I think we can safely say there's nothing too much bigger than Eris out there. Isn't that still smaller than our moon?
Mike Brown: For me, the fun thing to think about for "sizable" in the Kuiper belt is that fact that there was no equivalent to Clyde Tombaugh in the southern hemisphere. So it is not impossible that someday someone might find something as bright as Pluto moving in the south that could have been discovered 80 years ago but wasn't until now!
Mike Brown: Yeah, Eris is about half the size of the moon. Pretty pathetic, even I must admit.
Ian O'Neill: That's still impressive considering you managed to spot that little thing floating around - must have been like looking for a needle in a haystack!