Uranus may be the weirdest planet in our solar system, and the most complex simulation ever of its past could help us figure out why.
While most planets in our solar system spin on axes at right angles to the planes of their orbits, Uranus rotates on its side. It could not have formed that way, so most planetary scientists believe that, sometime in its past, a large space rock smashed into it and tipped it over.
Now Jacob Kegerreis at Durham University, UK, and his colleagues have used a supercomputer to build an advanced simulation of this event. They modelled Uranus and its impactor as a set of 100 million particles, and the result is a swirling, psychedelic video in which brightly coloured particles represent bits of rock, ice, and gas. As the impactor slams into Uranus, plumes of material spray outward and the interior of the planet is filled with whorls of mixing gas and plasma.
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The ultimate goal of the simulations is not just to create pretty pictures, but to understand exactly how Uranus got tilted. The team also hope to shed light on further mysteries, such as why Uranus doesn’t radiate heat like other gas giants and the origins of its strange, lumpy magnetic field.
“We’re pretty certain that a giant impact knocked Uranus over – what else did that cataclysmic event do?” says Kegerreis, who presented the work at a meeting of the American Geophysical Union in Washington DC last month. “We’ve only just started looking at the actual results, but we’re hoping to see an awfully long list of new and exciting things.”
There are already a couple of promising results. The simulation shows the core of the impactor being stretched into a pancake and then forming a layer around Uranus’ core, which may be keeping it from radiating heat outward. And chunks of metallic rock seem to get embedded in the planet, which could be messing with its magnetic field.
There’s only one problem: the simulation is far more detailed than any of the actual data we have on Uranus. “We can see a range of detailed differences between the different impacts in the simulation, but we don’t really know enough about the real-world system to know which one is more likely,” says Kegerreis. We’ll have to wait until someone sends a spaceship.
Article amended on 4 January 2019
We corrected our spelling of Jacob Kegerreis’s name
