New animation of the ultimate engineered solar system for a talk I'm giving tomorrow at a sci-fi convention in Lithuania.

It has 400 rocky planets in the habitable zone of a single Sun-like star

It's perfectly stable (I simulated it out to about a billion years)

planetplanet.net/2017/05/03/t...

Here's something new and weird -- eccentric rings of co-orbital planets.

They are stable indefinitely, from an orbital point of view.

Could they actually form and exist?

planetplanet.net/2025/09/02/e...

Like dinosaurs, Saturn and Jupiter roamed
They sculpted this system that humans call home

The gas giants roared, the system unstable
An ice giant planet fell right off the table!
A whole ring of comets was launched to the stars
The planets — bombarded — still bear the scars.

A quick update about co-orbital rings of planets.

This setup -- with 42 planets (each the same mass as Earth) sharing an orbit that is the same average distance as Earth (1 au) but super-eccentric -- is stable for at least 5 million years. (I'm running it out to a billion years to test)

Blog post on #planetplanet about the paper: (Exo)Planet Nine strikes back!

planetplanet.net/2025/05/27/e...

3/

Hello what have we here?

I didn't think this would be stable, but it is! (Planets are 1 Earth-mass each)

Fun fact: if you throw darts completely randomly at a regulation dartboard, it will take ~199 to hit the outer bullseye and 1261 to hit the inner bullseye!