Dr. Evgenya Shkolnik
Dr. Evgenya Shkolnik Astronomer, Lowell Observatory
Our Jupiter is not a hot Jupiter because it didn't migrate through the original planet-forming disk into the center. So we believe that these hot Jupiters could not have formed; there's no model that can make a hot Jupiter form at a three-day orbit.
There's just not enough material in that gassy, dusty disk to put into this giant planet, so it must have formed far out, at around 5 or 10AU, and migrated its way inward. Now, our Jupiter, for various reasons, did not do that, probably because it was interacting with Saturn. It had Saturn, which was another massive planet, next to it, and the dance that they were doing prevented it from coming inward all the way and then stopping at a three-day orbit, which is good for us. Because had it done that, the terrestrial planets probably would never have formed, and if they had, they would have been ejected from the system.
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