Hot Jupiter’s, possible water worlds or gas dwarfs, even one planet that could have a mantle of diamond, exo-solar planets remind us that the universe can still harbor secrets. In the last decade or two, as the number of strange exo-planetary denizens grew, it became clear that some must have migrated. Moved closer, or shot away, from their primary star. The early history of our own solar system, how the planets formed and ended up in the relatively stable configuration we see today, can be studied with the same techniques developed and refined to model those alien systems. One of the simulations that best explains the familiar worlds we know huddling around the sun comes with an extra planet, or maybe two: [Read more…]