450P/LONEOS centaur observed transforming into an active comet

Astronomers have observed the first direct transformation of a centaur—a class of icy celestial bodies orbiting between Jupiter and Neptune—into an active comet. The object, identified as 450P/LONEOS, was discovered in 2004 and has recently begun exhibiting cometary behavior, including the formation of a coma consisting of gas and dust.

Research led by Charles Schambeau of the University of Central Florida indicates that a close gravitational encounter with Saturn in 1992 altered the object's orbit, pushing it closer to the Sun. Observations from the Gemini North telescope in Hawaii and the James Webb Space Telescope revealed that the activity is driven by carbon dioxide rather than water vapor. Because the object is still relatively far from the Sun, water ice cannot sublimate effectively; instead, the release of trapped carbon dioxide from its porous, amorphous structure is fueling the development of its tail.

This discovery provides a critical link in understanding how inactive icy bodies in the outer solar system evolve into active comets.