The Solar System's giant planets are in pretty odd orbits: they all have large obliquities, that is they have a large inclination of the spin axis with respect to the orbital plane. These orbits have been attributed to grazing collisions with Earth-sized planetoids billions of years ago. But this hypothesis does not explain all the observations. Adri?n Brunini presents an alternative model in which the giant planets acquired large obliquities by mutual gravitational interaction during their formation. This new simulation provides support for a Solar System model that involves rapid migration of the giant planets to new positions after a long period of stability.

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text credit nature.com