An Earth-Sized Protoplanet Crashed Into Uranus, Tilted the Planet and Created Its Moons

Monday, 18 December 2017 - 3:16PM
Monday, 18 December 2017 - 3:16PM
An Earth-Sized Protoplanet Crashed Into Uranus, Tilted the Planet and Created Its Moons
Image credit: YouTube
Uranus has 27 known moons, but how they all came to orbit the planet has long been one of our solar system's great mysteries—until now.

Japanese researchers recently announced that Uranus was likely knocked on its side by a giant, Earth-sized protoplanet that flipped the planet and created new moons in the process. 

While 18 of the planet's moons orbit around its equator, researchers found that nine of the moons followed an irregular orbit that deviates from the equator. 

Combined with prior research, they concluded those moons were formed after Uranus itself came into existence following a "giant impact scenario." 

Lead research author Yuyi Ishizawa supported these claims using a computer simulation that showed a gigantic cosmic collision giving Uranus its tilt, and chipping off rubble that formed the irregular moons. "Material from the two bodies is ejected in a debris disk, and finally satellites are formed from the debris disk," he said. "It is possible to explain the axial tilt and the formation of regular satellites of Uranus simultaneously."

Uranus has a particularly unusual axial tilt; no other planet in our solar system is tilted that much. 

While the poles of most planets are pointed the same way as the sun, Uranus' axis of spin is tilted 98 degrees, almost on its side. 

If true, Ishizawa's research recalls the "Giant-impact hypothesis" that suggests our own planet's moon was also created by rubble following Earth's collision with a huge, astronomical body the size of Mars about 4.5 billion years ago. 

Just in case all this talk of cataclysmic planetary collisions has made you nervous, remember that the Earth is going to be fine—we've got at least 800 years before all life on the planet is wiped out by an asteroid. We'll be dead by then, so no worries. 
Science
Space
An Earth-Sized Protoplanet Crashed Into Uranus, Tilted the Planet and Created Its Moons