SHEFFIELD, United Kingdom — If you think the controversy over calling Pluto a planet is the only thing happening at the edge of our solar system, think again! Researchers say there’s a unique dwarf planet with rings which defy the laws of physics sitting at the outer reaches of the solar system. Astronomers say the rings encircling a mysterious world named Quaoar are more than twice as far out as the rings of Saturn, Jupiter, Neptune, and Uranus.
The discovery is forcing scientists to rethink the origins of these structures. Astronomers discovered this dwarf planet after it passed in front of a background star as it orbited the Sun. The event lasting less than a minute was preceded and followed by two dips in light — indicative of a ring system.
“It was unexpected to discover this new ring system in our Solar System, and it was doubly unexpected to find the rings so far out from Quaoar, challenging our previous notions of how such rings form,” says study co-author Professor Vik Dhillon from the University of Sheffield’s Department of Physics and Astronomy in a media release.
Why do these rings defy belief?
An international team analyzed images from HiPERCAM – an extremely sensitive high-speed camera. It was developed at the University of Sheffield and has been mounted on the world’s largest optical telescope on La Palma in the Canaries.
Ring systems are rare. Only two other minor planets are known to possess them, Chariklo and Haumea. They are able to survive because they orbit close to the parent body. Tidal forces prevent the material from clumping together and forming moons.
What makes Quaoar’s rings so remarkable is it lies at a distance of over seven planetary radii — twice as far out as what was previously thought to be possible. Saturn’s famous rings, for instance, are within three planetary radii. The study, published in the journal Nature, may provide new insights into their creation billions of years ago.
“The use of our high-speed camera – HiPERCAM – was key to this discovery as the event lasted less than one minute and the rings are too small and faint to see in a direct image,” Prof. Dhillon says. “Everyone learns about Saturn’s magnificent rings when they’re a child, so hopefully this new finding will provide further insight into how they came to be.”
Quaoar is named after a Native American god. It lies a 620 million miles beyond Pluto. It moves around the Sun every 288 years in a near-perfect circle. NASA’s Hubble Space Telescope measured it at 690 miles wide, 250 miles wider than the biggest main-belt asteroid Ceres and more than half the diameter of Pluto itself. It’s the largest object in the solar system seen since the discovery of Pluto in 1930.
South West News Service writer Mark Waghorn contributed to this report.