Quaoar, a dwarf planet in our solar system, has a ring of debris orbiting it that is far further out than we thought the laws of physics allow
The dwarf planet Quaoar has a ring (not shown in this visualisation) that shouldn't be able to exist Andamati/Shutterstock
The dwarf planet Quaoar, which sits beyond Neptune in our solar system, appears to have a ring of debris around it that is much further out than was thought possible.
"We have observed a ring that shouldn't be there," says Bruno Morgado at the Federal University of Rio de Janeiro in Brazil.
Until now, every ring or orbiting moon observed by astronomers has obeyed a limit put forward by astronomer Édouard Roche in 1848 that relates to its distance from a parent body. If an object is below the Roche limit, its parent body's gravity rips apart the orbiting object into a collection of smaller chunks which eventually form a ring, like those seen around Saturn. Outside that limit, dust and debris should coalesce to form larger objects, such as moons.
Quaoar, which is 1110 kilometres across and is slightly less dense than our moon, should have only moons beyond a distance of 2.4 times its radius of 555 kilometres, but Morgado and his colleagues measured the ring at 7.2 times Quaoar's radius.…
Alex Wilkins
www.newscientist.com