Mysterious rogue planet ‘smashed into Uranus’ and changed it forever


A planet twice the size of Earth gave our most unfortunately named planet its odd tilt.

In the early history of the solar system, a mysterious planet twice the size of Earth smashed into Uranus, changing the ice giant forever.

The impact left the planet tilted sideways, and could account for how cold it is.

Astronomers at Durham University, UK ran the first high-resolution computer simulations of different massive collisions with the ice giant to try to work out how the planet evolved.

The research confirms a previous study which said that Uranus’ tilted position was caused by a collision with a massive object.

It was most likely a young protoplanet made of rock and ice – during the formation of the solar system about 4 billion years ago.

Scientists reveal what Uranus smells like (Getty)
Scientists reveal what Uranus smells like (Getty)

The simulations also suggested that debris could form a thin shell near the edge of the planet’s ice layer and trap the heat emanating from Uranus’ core.

The trapping of this internal heat could in part help explain Uranus’ extremely cold temperature of the planet’s outer atmosphere (-216 degrees Celsius), the researchers said.

The findings are published in The Astrophysical Journal.


Lead author Jacob Kegerreis, PhD researcher in Durham University’s Institute for Computational Cosmology, said: ‘Uranus spins on its side, with its axis pointing almost at right angles to those of all the other planets in the solar system. This was almost certainly caused by a giant impact, but we know very little about how this actually happened and how else such a violent event affected the planet.

‘We ran more than 50 different impact scenarios using a high-powered super computer to see if we could recreate the conditions that shaped the planet’s evolution.

‘Our findings confirm that the most likely outcome was that the young Uranus was involved in a cataclysmic collision with an object twice the mass of Earth, if not larger, knocking it onto its side and setting in process the events that helped create the planet we see today.’

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