New images from astronomer Gianluca Masi show Comet C/2025 K1 (ATLAS) has fragmented into multiple pieces after surviving a close perihelion on Oct. 8. The breakup followed a sudden brightening that changed the comet's color from green to gold, possibly indicating fewer carbon-bearing molecules in its coma. The fragments are located in the constellation Leo at about magnitude 9.9 and should be visible with a good amateur telescope or binoculars. The debris is expected to make its closest approach to Earth on Nov. 25 at roughly 37 million miles (60 million km).
New Image Shows Comet C/2025 K1 (ATLAS) Breaking Apart — Fragments to Pass Near Earth on Nov. 25
New images from astronomer Gianluca Masi show Comet C/2025 K1 (ATLAS) has fragmented into multiple pieces after surviving a close perihelion on Oct. 8. The breakup followed a sudden brightening that changed the comet's color from green to gold, possibly indicating fewer carbon-bearing molecules in its coma. The fragments are located in the constellation Leo at about magnitude 9.9 and should be visible with a good amateur telescope or binoculars. The debris is expected to make its closest approach to Earth on Nov. 25 at roughly 37 million miles (60 million km).
11:12 AM, 11/14/2025Science
Comet C/2025 K1 (ATLAS) Fragments After Close Solar Passage
New observations reveal that Comet C/2025 K1 (ATLAS) has disintegrated into multiple fragments, forming a cloud of debris streaming away from what was once a single nucleus. The discovery was made with images captured by astronomer Gianluca Masi in Manciano, Italy, and shared via The Virtual Telescope Project.
The object was discovered in May by the Asteroid Terrestrial-impact Last Alert System (ATLAS) and reached perihelion — its closest approach to the Sun — on Oct. 8. Although it shares a partial name with the interstellar visitor 3I/ATLAS, the two are unrelated beyond being detected by the same telescope network around the same time.
"Several parts (sub-nuclei or clouds of debris) are visible, also a plume just below the leading fragment," Masi reported after reviewing the new images.
Initial measurements suggested C/2025 K1 survived a solar passage at roughly 31 million miles (50 million kilometers) from the Sun. However, recent images show the comet has split into several sub-nuclei and debris clouds — a breakup likely driven by thermal stress and gravitational forces experienced near perihelion.
Brightening and Color Change
Near perihelion the comet experienced a sudden brightening that coincided with a dramatic change in appearance: it shifted from the greenish tint commonly produced by diatomic carbon (C2) fluorescing in sunlight to a streaking ribbon of gold. The precise cause of the color change is not yet settled, but some scientists suggest the golden hue could indicate a relative depletion of carbon-bearing molecules in the coma (the cloud of ice, gas and dust around the nucleus), revealing different dust or gas components.
Where and How to See It
C/2025 K1 is currently located in the constellation Leo and is reported at about magnitude 9.9 (The Sky Live). For context, lower magnitude numbers indicate brighter objects; Regulus, Leo's brightest star, has an apparent magnitude near 1.35. At magnitude 9.9 the comet is too faint for the naked eye but should be visible with a good amateur telescope or a quality pair of stargazing binoculars under dark skies.
Closest approach: Whatever fragments remain are expected to pass nearest to Earth on Nov. 25, at an estimated distance of roughly 37 million miles (60 million kilometers) — just under half the average distance between Earth and the Sun.
What This Means
Fragmentation is a common fate for comets that experience intense solar heating and tidal forces. While the breakup reduces the chance of a spectacular naked-eye display, it offers scientists an opportunity to study freshly exposed material and learn more about the comet's composition and structure.
Observation tip: Check current charts from sources like The Sky Live or the Virtual Telescope Project before observing, and use an equatorial mount or star charts to track the faint, moving target.