A distant comet is forming new rings while we watch in real time

For the first time, astronomers are observing the formation of a ring system in real time. The rings in question surround Chiron, a comet-like object that orbits the Sun between the orbits of Saturn and Uranus. Every time we look at Chiron, its rings seem a little different.

Chiron is not the first small object around which we have observed rings: the asteroid Chariklo and the dwarf planets Haumea and Quaoar There are also small ring systems. All of these rings were discovered using a technique called stellar occultation, which involves waiting for an object to pass in front of a distant star and then creating a map of how the star's light is blocked by orbital material.

“There are only about 20 objects that have been observed through stellar occultations, so seeing four of them with rings is a high statistic,” says Bruno Sicardi at the Paris Observatory in France. “There are hundreds or thousands of bodies, so there must be hundreds of ring systems.” He expects we'll find even more in the coming years.

Sicardi and his colleagues examined a stellar eclipse that occurred in 2023 to determine the structure of the rings around Chiron. While previous observations had indicated the likely presence of three rings, this new observation revealed an additional disk of material surrounding these rings and extending further from Chiron's surface, as well as another ring even further away that had never been observed before.

“Nature shows us the ring in its formative stage, which is very fortunate for us because when we look at the rings of Saturn, the rings of Uranus or even the rings of Chariklo, they are essentially always the same,” says Sicardi.

There are many different ways rings may formbut observing their formation as it develops could help us understand them much more deeply than we do now. “[This could] “will shed light on the specific conditions that allow rings to form, persist, or dissipate, and may ultimately explain why such systems are found only in cold, icy regions of the Solar System,” says a team member. Christian Pereira at the National Observatory of Brazil.