Published on 22/01/2013
I understand that astronomers believe so-called rogue planets were likely ejected from their solar systems early in their planetary histories, but it's never clear what event(s) could trigger such a thing. My question: What kind of a catastrophic event in our solar system could cause the Earth to become a rogue planet today? It's ok to be speculative. I'd love to know. Thank you.
Planetary systems become unstable when the orbits of two planets cross. By this I don't mean that the planets collide, rather, that their crossing orbits cause them to have a close gravitational encounter. The close gravitational encounter can transfer a tremendous amount of orbital energy from one planet to the other, potentially shooting it out of the planetary system.
In summary, to make the Earth a "rogue planet," the Solar system would have to evolve such that another large body (a large asteroid, or Venus or Mars, or eventually Jupiter) crossed orbits with the Earth. The asteroids and Mars probably don't have enough energy to eject Earth. A more massive planet like Jupiter would be more effective at ejecting Earth, but Jupiter is quite far away and is less likely to cross orbits with Earth. But the Solar system is definitely stable for the durations of our lives, and this kind of ejection couldn't happen for at least a few tens of millions of years, if not billions.
Page last updated: 22 January 2013 at 16:58