A recent study suggests that Uranus, the penultimate planet in our system, was struck by a huge object about 3.5 billion years ago. A celestial “crash” that would explain its axis of rotation different from other planets.
Uranus has a special feature: its axis of rotation is 90% inclined relative to its orbit. Thus, the planet seems to roll in its orbit while the others behave like tops. What has happened to the planet? A team of astronomers now offers an explanation: Uranus was struck by a body at least twice as big as Earth.
“Comprehensive computer simulations show that a huge rock crashed on the seventh planet in our system,” says Jacob Kegerreis of Durham University (UK) and lead author of the study. “Uranus is unique. The massive planet tilts about 90 degrees to its side, as do its five largest moons. Its magnetic field is also unbalanced. It’s very strange,” he adds.
These new simulations propose here a gigantic collision between Uranus and a body twice bigger than our planet. The latter, according to the researchers, could still be lurking in the recesses of the solar system. It could also explain the deviated orbits of some small bodies in the Kuiper belt. “It could fit with the theory that a planet X orbits the Sun far beyond Pluto,” says the researcher.
This collision, the researchers estimate, could have occurred between 3 and 4 billion years ago, very soon after the formation of the planet, and probably before the formation of the largest moons of Uranus. A disc of matter would then have formed around the planet, finally forming the satellites observed today. Uranus would then have led its five largest moons to adopt the same strange inclination (with its tidal forces).
This collision could also explain the extremely low temperature (-216 ° C) of the Uranus atmosphere. It is indeed possible that the debris of the object impacting the planet formed a kind of “shell” in the lower atmosphere, preventing the heat of the center from moving towards the upper atmosphere