The "other" Comet ATLAS has fragmented, transforming into a cloud of debris that's streaming into space, new observations have revealed.
The comet, called C/2025 K1 (ATLAS), was discovered in May by astronomers at the Asteroid Terrestrial-impact Last Alert System (ATLAS) and passed perihelion, or closest point to the sun, on Oct. 8. It has no relation to the famous interstellar comet 3I/ATLAS, other than having been discovered by the same telescope network around the same time.
Initial observations appeared to suggest that Comet K1 survived its passage around our star at a minimum distance of 31 million miles (50 million kilometers), or roughly four times closer than Comet 3I/ATLAS got.
However, new observations taken by astronomer Gianluca Masi in Manciano, Italy, show that the gravitational strain of its voyage around the sun was too much for the comet, causing it to fragment into several pieces, or clouds.
"Several parts (sub-nuclei or clouds of debris) are visible, also a plume just below the leading (the first from the left) fragment," Masi, an astronomer at the Astronomical Observatory of Campo Catino and the founder of The Virtual Telescope Project, wrote in an update.
C/2025 K1's disintegration was portended by a sudden brightening event around perihelion, which saw the comet transform from the greenish hue seen in many comets that fly close to our sun (caused by the presence of diatomic carbon fluorescing in sunlight) into a streaking ribbon of gold.
The cause of this transformation is unclear; some scientists speculate that the change in color had something to do with a relative lack of carbon-bearing molecules in the comet's coma (the cloud of ice, gas and dust around the comet's body).
If you want to see the exploded comet for yourself, look in the constellation Leo, where it's shining at magnitude 9.9, according to The Sky Live. (In astronomy, a lower magnitude corresponds to a brighter object; Regulus, the brightest star in Leo, has an apparent magnitude of about 1.35, for example.) Although the comet is still too dim to be seen with the naked eye, it can be spotted with a good telescope or a pair of stargazing binoculars.
Whatever survives of the comet is set to pass closest to Earth on Nov. 25. It will come within about 37 million miles (60 million km), or just under half the average distance between Earth and the sun.
