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Planet Nine: Solar System renegade?

We are discussing the origins of Planet Nine.  In part 1 we explored whether it could have been produced during an orbital instability in the early Solar System.  In part 2 we showed that Planet Nine could have been captured from another star.  Here we will explore another plausible idea that is a little less…

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Planet Nine: an intruder among us?

We are discussing the origins of Planet Nine.  In part 1 we explored whether it could have been produced during an orbital instability in the early Solar System.  Here we will explore a much more exotic origin. Scenario 2.  Planet Nine is a planet that formed around another star and was captured by the Sun…

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Is the Solar System special?

There are at least three aspects of the Solar System that are weird or at least unusual: No hot super-Earths.  About half of stars contain a planet larger than Earth interior to Venus’ orbit.  We don’t have one.  That puts us in the minority. Jupiter.  Only about 15% of Sun-lilke stars appear to have gas…