Hubble Snaps a Comet as It Splits Apart in Space

NASA’s latest Hubble images show comet C/2025 K1 ATLAS breaking apart over three days in November 2025, which astronomers had not anticipated. They’d chosen to examine this comet as a last resort because their first pick had proven impossible to observe due to the limitations of their equipment, and, as if the universe was waving in their faces, the comet began to split apart just as they were getting a good look.

Comet C/2025 K1 ATLAS initially appeared on sky surveys in May 2025. It’s an ancient long-period comet from the extreme limits of our solar system. By October, it had passed the sun, passing within one-third of the distance between Earth and the sun, a scorcher that was putting its icy structure to the test. In May, it was slightly larger than most comets, measuring around five million feet wide.

The scientists captured a magnificent close-up of the process by using Hubble to take fast 20-second exposures of the comet each day, thanks to the imaging spectrograph and cosmic beginnings spectrograph included in the package. The comet was already 250 million miles away from Earth at the time, in the constellation Pisces and on its way out of the solar system for good, yet Hubble could detect a faint glow. What was visible to ground-based telescopes was virtually nothing. Each of the comet’s four major fragments was accompanied by its own cloud of gas and dust, and then there was this tiny little fragment that began to break apart directly in front of the telescope.

It appears that the break-up began around 8 days before the photographs were captured, which is significantly earlier than is typical in similar situations, with images of pre-breakup comets typically appearing weeks or even months later. Scientists went back through the photographs and determined how the breakdown occurred. Over the course of three days, the fragments gradually drifted apart, leaving their own clouds visible for an extended period of time.

One thing that instantly caught the researchers’ eye was that the break-up exposed new ice, although the bright eruptions visible from Earth took a long to occur. Most comets seem to us as a result of sunlight bouncing off dust, with the ice doing little to enhance the vision. Scientists believe this is due to a thin layer of dry dust on the surface that eventually blows off, or that heat from the sun seeps in and forces out the expanding shells of material.

John Noonan of Auburn University was the first to spot the four distinct objects in the images, and he was quick to point out just how unlikely it was that they had happened to be watching at the exact moment a comet began tearing itself apart. His colleague Dennis Bodewits echoed that sentiment, noting that a routine target they had essentially picked at random had chosen the perfect moment to break up.