On October 8, comet C/2025 K1 (ATLAS) made a dramatic close pass to the Sun, coming within 49 million kilometers (31 million miles). This close encounter is rare. Many were thrilled when the comet returned and became visible again, but unfortunately, it recently broke apart.
While 2025 hasn’t seen a “Great Comet” like Hale-Bopp in 1997, it has certainly been memorable for comet watchers. C/2025 K1 (ATLAS) was one of three notable green comets this year, along with C/2025 R2 (SWAN) and C/2025 A6 (Lemmon). Lemmon stood out as the brightest of the bunch. Also, let’s not forget our interstellar visitor, 3I/ATLAS, adding to the excitement.
According to Italy’s National Institute of Astrophysics (INAF), on the night of November 11-12, K1 broke into at least two large fragments and smaller pieces. The two main fragments are about 2 kilometers apart in space images. A potential third piece is also nearby.
A fascinating GIF from the Virtual Telescope Project captures this fragmentation. It shows the pieces spreading out over just a day.
K1 is expected to make its closest approach to Earth on November 24, 2025, at a distance of 60 million kilometers (37.3 million miles). It should be visible from the Northern Hemisphere, near Ursa Major, although its new broken state may impact its brightness.
Dr. Elena Mazzotta Epifani from INAF noted that the breakup of such comets is not just visually spectacular but provides valuable scientific insights, especially since K1 is a “new” comet. Having formed in the Oort Cloud, this is its first journey toward the Sun, making its fragmentation even more intriguing.
The comet’s uniqueness doesn’t stop there. It has an unusual composition, being carbon-poor, a trait shared with only two other known comets. Recently, its color shifted from green to a golden brown, as captured in stunning photos by astrophotographer Dan Bartlett, who recently won the Astronomy Photographer of the Year 2025 award.
The color changes of a comet depend on its molecular makeup and dust output, which can vary during close encounters. This shift might have led to an increase in dust output, creating the beautiful golden hue while also weakening K1’s core.
As the date for its closest Earth pass approaches, astronomers are eager to observe the comet. While it may not be as visually stunning now, it has become a fascinating case study for scientists. Keep an eye on it—there’s more to discover.
