From the outer reaches of our solar system, astronomers have discovered a remarkable sight: a ring around a Pluto-sized dwarf planet called Quaoar. What makes this discovery even more extraordinary is that the ring is located far further away from the planet than is typical, calling into question how such systems form.
Using a powerful telescope on La Palma, researchers observed a sharp dip in starlight as Quaoar passed in front of the star. Intriguingly, two smaller dips, before and after, were also observed, which the astronomers realised indicated the presence of a ring system. The ring is located at a distance of more than seven planetary radii, twice as far out as what was previously thought to be the maximum radius, known as the Roche limit.
The latest observations confound existing theories, as the debris in the ring should have amalgamated into a moon if it were located inside the Roche limit. One idea is that the debris is “less sticky”, meaning that fragments in the ring are more likely to bounce off each other during collisions.
The team are exploring various possibilities for how the distant ring could remain stable, and their findings could provide further insight into how Saturn’s magnificent rings came to be. This remarkable discovery is sure to inspire further research into the outer reaches of our solar system.