Dr. Katherine Volk

What would we have seen because of where we looked in the sky?

And the answer is we would see exactly what we saw.

So it's perfectly consistent with a random intrinsic distribution and the clustering just being an effect of where we looked.

It's hard to say that for the other surveys because not every survey characterizes their detection efficiencies very well.

So it's actually really hard to take this whole data sample and back that back out.

This was the source of much of the heated debate at the meeting the other week.

The survey I'm part of is led by Canadians.

They were a little more polite, I think, in the arguing.

But strongly held opinions on both sides of this.

So your mileage may vary depending on who you ask about whether the clustering is significant.

But there are some other hints that maybe would be a good line of evidence for a possible large planet like this, this Planet 9.

One thing that Renyu Mahatra in this department noticed when she was looking at these extreme Kuiper Belt objects is that their orbital periods appeared to be related to each other.

Because they were nice integer ratios when you divided their orbital periods by each other.

And that wouldn't make any sense for them to have an effect on each other gravitationally.

These are small objects.

But what would make sense is if there was a planet out there that they are all in an orbital resonance with.

So their periods are not related to each other, but they're all related to the planet, and therefore they appear to be related to each other.

So just a reminder of what an orbital resonance is.

Pluto's in an orbital resonance with Neptune.

It's in the three to two resonance, which means that for every three times Neptune goes around the sun, Pluto orbits exactly twice.