The solar system is full of ringed bodies. There’s Saturn, of course. Plus Jupiter, Uranus and Neptune. The asteroid Chariklo and the dwarf planet Haumea sport rings, too. All those rings lie within or near a mathematically determined distance of their parent bodies. But now, the dwarf planet Quaoar has been found with a ring that breaks this rule. Quaoar’s ring circles the dwarf planet much farther out than should be possible.
“For Quaoar, for the ring to be outside this limit is very, very strange,” says Bruno Morgado. He’s an astronomer at the Federal University of Rio de Janeiro in Brazil. He and his colleagues shared the discovery of Quaoar’s strange ring February 8 in Nature. The finding may force scientists to rethink the rules governing planetary rings.
Getting a glimpse of Quaoar
Quaoar (KWAH-war) is a dwarf planet. That is, it’s a round world orbiting the sun that is not quite big enough to be a planet. An icy body about half the size of Pluto, Quaoar is located in the Kuiper Belt at the solar system’s edge. That far away from Earth, it’s hard to get a clear picture of this frigid world.
Morgado and his colleagues watched Quaoar block the light from a distant star. The timing of the star winking in and out of view can reveal details about Quaoar, like its size and whether it has an atmosphere.
The researchers looked at data from Quaoar passing in front of stars from 2018 to 2020. Those data came from telescopes all over the world, such as in Namibia, Australia and Grenada. Some observations also came from telescopes in space.
There was no sign that Quaoar had an atmosphere. But surprisingly, it did have a ring. Even more surprisingly, Morgado says, “the ring is…
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