An international team of astronomers has found an explanation for Uranus’s strange climate. Their research shows that the planet had a cataclysmic collision with an object roughly twice the size of Earth, which caused it to tilt.
The study published in The Astrophysical Journal builds on a previous research that suggested that the tilted position of the ice giant was caused by a collision with a massive object, most likely a young proto-planet made of rock and ice during the formation of the solar system about four billion years ago.
The researchers have investigated high-resolution computer simulations of different massive collisions with the ice giant to understand how the planet has evolved.
The simulations suggest that debris from the impactor could have formed a thin shell near the edge of the planet’s ice layer, trapping the heat emanating from Uranus’ core. The trapping of this internal heat could in part help explain the extremely cold temperature of the planet’s outer atmosphere, which lies at – 216 degrees Celsius.
The paper’s lead author Jacob Kegerreis, a researcher in Durham University’s Institute for Computational Cosmology, has been quoted as saying in a statement, “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.”
“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,” he says, “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.”
According to the simulations, the object struck a grazing blow on the Uranus and then moved off into space. This collision was strong enough to affect the tilt of the planet, but not enough to destroy its atmosphere.
The research can also explain the formation of Uranus’ rings and moons, since the simulations suggest that the impact could have jettisoned rock and ice into orbit around the planet. This rock and ice could have then clumped together to form the planet’s inner satellites and perhaps altered the rotation of any pre-existing moons already orbiting Uranus, according to the study.
Uranus is similar to the most common type of exoplanets – planets found outside of our solar system – and researchers hope that their findings will help explain how those other planets have evolved and what they may be made of.