NCCR PlanetS: Why Uranus & Neptune Are Different

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NCCR PlanetS: Why Uranus & Neptune Are Different

Post by bystander » Tue Feb 04, 2020 5:26 pm

Why Uranus and Neptune Are Different
Swiss National Center of Competence in Research, PlanetS | 2020 Feb 04

The two outermost giant planets of the Solar system have similar masses but there are also striking differences. Researchers of the NCCR PlanetS at the University of Zurich have found an explanation for this long-standing unsolved mystery: Two different giant impacts could have had completely separate effects.

Uranus and Neptune are the outermost planets of the Solar system. In size, possibly bulk composition, and their large distance from the Sun they are similar and clearly segregated from the inner terrestrial planets and the gas giants Jupiter and Saturn. “However, there are also striking differences between the two planets that require explanation”, says Christian Reinhardt, who studied Uranus and Neptune together with Alice Chau, Joachim Stadel and Ravit Helled, all PlanetS members working at the University of Zurich, Institute for Computational Science. “For example, Uranus and its major satellites are tilted about 97 degrees into the Solar plane and the planet effectively rotates retrograde with respect to the Sun.” clarifies Joachim Stadel.

Also, the satellite systems are different. Uranus’ major satellites are on regular orbits and tilted with the planet, which suggests that they formed from a disk, similar to Earth’s Moon. Triton instead, Neptune’s largest satellite, is very inclined and therefore most likely a captured object. Finally, they could also be very different in terms of heat fluxes and internal structure. ...

Bifurcation in the History of Uranus and Neptune: The Role of Giant Impacts ~ Christian Reinhardt et al
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