Two false-color views of Uranus, captured 90 minutes apart by the Hubble Space Telescope in 1997, show the rotation of the planet, the tilt of its polar axis and eight of 10 small moons discovered by the Voyager 2 spacecraft during its 1986 flyby. New research confirms the planet’s tilt was likely caused by a massive body slamming into Uranus during the formation of the solar system. Image: NASA/JPL/STScI
New computer simulations indicate a massive body twice the size of Earth or even larger crashed into Uranus during the formation of the solar system, knocking the gas giant on its side and possibly explaining to its colder-than-expected upper atmosphere and the formation of its rings and moons.
The research confirms a previous study that blamed such a collision with a protoplanet made up of rock and ice for Uranus’ oddball axial tilt – 97.77 degrees – roughly parallel to the plane of the solar system. As a result, the planet’s poles take turns facing the sun as Uranus swing around in its orbit, each experiencing 42 years of sunlight followed by 42 years of darkness. For comparison, Earth’s axis is tilted 23.5 degrees.
“Uranus spins on its side, with its ...