Dr. Katherine Volk

So this is work that I did with Renu this past year that was recently published.

And this has to do with affecting the orbital planes of the more nearby Kuiper Belt objects.

So if we go back to this side-on view of the Kuiper Belt,

We see that there's this vertical structure, so these are all instantaneous positions of objects, but they're all on orbits, and those orbits have some tilt relative to the rest of the planets in the solar system.

And their average tilt, if you just took this snapshot and said, what is the average plane they're all in?

That's set by the mass distribution in the solar system.

to get a little bit into some physics here of why that is.

So if we look at how the planets behave, I think it's a little bit easier to understand.

So what we do in this sense to understand how the orbital planes evolve over time is we spread the planets out in their orbits and pretend that they're rings of mass.

Because we don't care where they are in their orbits.

We care about how their orbits tilt is evolving over time.

So we spread the planets out into these rings of mass.

And we look at how those rings of mass gravitationally interact with each other.

So they're all going to exert torques on each other because, of course, they're not perfectly coplanar.

Every planet has some little bit of random tilt.

And here I'm...

displaying that the line of nodes here where the planet is crossing the reference plane because I could not figure out how to get a reference plane to look nice in this little video I'm about to show so where it's black the orbit is above our reference plane and where it's gray the orbit is below so if you set these rings of mass in motion and calculate their mutual gravitational perturbations they start to precess or actually regress but the rings basically wobble around

and they all wobble around at different rates.

The amplitude of their inclinations relative to our reference plane is also varying in time and the line of nodes is going around.

This is very similar to a spinning top.