A ring that scientists had thought couldn’t exist has been found around a planet in our Solar System.
The ring is similar to those that famously wrap around other nearby planets, such as Saturn. But it was found on a much smaller world: the newly discovered dwarf planet Quaoar.
What’s more, the ring is much further away than scientists thought it could possibly be. The new ring is twice as far from Quaoar as researchers had thought was allowed by physics.
As such, it requires a rewrite of our understanding of the formation of planetary rings and the physics that govern them. That in turn could help us better understand the more famous rings around better known planets, such as Saturn and Jupiter.
But further work is required to better understand how the object can even exist at all, scientists say.
Together, the dwarf planet and its ring orbit the Sun, beyond Neptune, and represent just the seventh such system to be found.
The discovery was made by an international team of astronomers using HiPERCAM - an extremely sensitive high-speed camera developed by scientists at the University of Sheffield.
It is mounted on the world’s largest optical telescope, the 10.4 metre diameter Gran Telescopio Canarias on La Palma.
Because the rings are too faint to see directly in an image, the discovery was made by observing an occultation - when the light from a background star was blocked by Quaoar as it orbits the Sun.
Although the event lasted less than a minute, it was unexpectedly preceded and followed by two dips in light, indicative of a ring system around Quaoar.
Ring systems are relatively rare in the Solar System, and as well as those around Saturn, Jupiter, Uranus and Neptune, only two minor planets possess rings - Chariklo and Haumea.
All of the previously known ring systems are able to survive because they orbit close to the parent body.
According to the astronomers, what makes the ring system around Quaoar remarkable is that it lies at a distance of over seven planetary radii - twice as far out as what was previously thought to be the maximum limit, which is the outer limits of where ring systems were thought to be able to survive.
Therefore the discovery has forced a rethink on theories of ring formation.
Professor Vik Dhillon, co-author of the study from the University of Sheffield’s department of physics and astronomy, said: “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.
“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.
“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.”
The study, published in Nature, involved 59 academics from all over the world and was partly funded by the Science and Technology Facilities Council, and included six UK universities - Sheffield, Edinburgh, St Andrews, Warwick, Birmingham, and the Open University.
Additional reporting by Press Association