
A collisionless scenario for Uranus tilting (2009) - networked
https://arxiv.org/abs/0912.0181
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simonebrunozzi
Summary of the paper:

The origin of the high inclination of Uranus' spin-axis (Uranus' obliquity) is
one of the great unanswered questions about the Solar system. Giant planets
are believed to form with nearly zero obliquity, and it has been shown that
the present behaviour of Uranus' spin is essentially stable. Several attempts
were made in order to solve this problem. Here we report numerical simulations
showing that Uranus' axis can be tilted during the planetary migration,
without the need of a giant impact, provided that the planet had an additional
satellite and a temporary large inclination. This might have happened during
the giant planet instability phase described in the Nice model. In our
scenario, the satellite is ejected after the tilt by a close encounter at the
end of the migration. This model can both explain Uranus' large obliquity and
bring new constraints on the planet orbital evolution.

