Chaos in the Early Solar System

[Posteritatis]

Maybe we should take a break from dealing with Apollo deniers to have a look at a simulation of the early Solar System over at Sky and Telescope:

In the September 2007 issue of Sky & Telescope (page 22), Mark Littmann describes the fascinating finding of how celestial dynamicists collaborated to discover that an intense game of interplanetary billiards led to our current arrangement of planets and smaller bodies.

Alessandro Morbidelli (Cote d’Azur Observatory, France), Rodney Gomes (National Observatory of Brazil), Kleomenis Tsiganis (Aristotle University of Thessaloniki, Greece), and Hal Levison (Southwest Research Institute, Colorado) worked together to create their Nice model, which revealed that over the course of a billion years, trillions of gravitational encounters with small planetesimals gradually altered the orbits of the outer planets.

There's a video attached, in which, as the article puts it, "all hell breaks loose" about 878 million years into the system's history as the system is abruptly cleared of most of the junk left over from its formation. It's a good description, and it's interesting how sudden (in astronomical terms!) some changes can occur.

[Odin2005]

1. Wow, Neptune and Uranus went loco!

That must be what caused the "Late Heavy Bombardment" phase around 3.9 Billion years ago.