# Centaur 450P/LONEOS comet transformation

> Live situation record from CLSTR: https://clstr.news/situations/centaur-450ploneos-comet-transformation
> Updated: 2026-09-06T09:02:02.000Z. Sources: 11. Developments: 2.

Astronomers have documented 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 originally discovered in 2004.

Research indicates that a close gravitational encounter with Saturn in 1992 altered the object’s orbit, moving it closer to the Sun. Observations from the Gemini North telescope and the James Webb Space Telescope revealed the formation of a coma consisting of gas and dust. 

Scientists determined that the activity is primarily driven by the release of trapped carbon dioxide rather than water vapor, as the object remains too far from the Sun for water ice to sublimate effectively. This transition provides a critical link in understanding how inactive icy bodies in the outer solar system evolve into active comets, with researchers suggesting future gravitational influences could eventually transition 450P into a Jupiter-family comet.

## Claims

- Astronomers have observed a frozen celestial body, known as a centaur, transforming into a comet for the first time. (corroborated by 3 sources)
- The object, identified as 450P/LONEOS, was discovered in 2004. (corroborated by 3 sources)
- In 1992, the object passed approximately 4.6 million kilometers from Saturn, which altered its orbit. (corroborated by 3 sources)
- Observations from the Gemini North telescope in Hawaii identified a cloud of gas and dust around the object's core. (corroborated by 3 sources)
- Data from the James Webb Space Telescope revealed carbon dioxide gas and crystallized ice particles within the cloud. (corroborated by 3 sources)
- Carbon dioxide, rather than water vapor, is the direct trigger for the gas release and comet-like activity at this distance from the Sun. (corroborated by 3 sources)

## Timeline

### 2026-09-06: 450P/LONEOS centaur observed transforming into a comet

Astronomers have captured the first observation of a centaur, 450P/LONEOS, transforming into an active comet due to solar heating and carbon dioxide sublimation.

4 sources. https://clstr.news/cluster/450ploneos-centaur-observed-transforming-into-a-comet

### 2026-09-03: 450P/LONEOS centaur observed transforming into an active comet

Astronomers have captured the first direct observation of a centaur, 450P/LONEOS, transforming into an active comet, driven by carbon dioxide release as it moves closer to the Sun.

7 sources. https://clstr.news/cluster/450ploneos-observed-transforming-from-a-centaur-into-a-comet

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Cite as: Centaur 450P/LONEOS comet transformation. CLSTR, https://clstr.news/situations/centaur-450ploneos-comet-transformation