JWST Detected an Icy World Beyond Jupiter Transforming Into a Comet

The icy Centaur 450P/LONEOS may preserve material left over from the Solar System’s formation, but a pass within 2.9 million miles of Saturn in 1992 abruptly shifted its orbit closer to the Sun; now Gemini and JWST have detected its returning coma, carbon-dioxide gas and rising dust production, giving astronomers a rare real-time view of a Centaur beginning its transition into a Jupiter-family comet.

A close pass by Saturn in 1992 lasted only hours, but it may have changed the next stage of a small world’s life. The icy body now called 450P/LONEOS came within about 4.6 million kilometres of the giant planet, close enough for Saturn’s gravity to pull its orbit markedly inward. That did not produce an instant plume. Heat takes time to move through a porous, insulating nucleus. More than two decades later, Gemini North began following the objec…

JWST detected an icy world beyond Jupiter transforming into a comet

JWST detected CO₂ and icy dust around Centaur 450P/LONEOS, revealing how a frozen outer solar system body may become comet-like.