Comet Spin Flip: First-Ever Reversal Observed by Hubble Telescope

Astronomers have, for the first time, observed a comet changing the direction of its rotation, a phenomenon detected using the Hubble Space Telescope. The small comet, designated 41P, initially slowed its spin before reversing direction entirely, according to observations released this week.

The discovery provides a dramatic example of how volatile activity can influence the spin and physical evolution of small bodies in the solar system. The findings were made possible by the Hubble Space Telescope’s unique capabilities, allowing scientists to track the comet’s subtle changes over time.

While comets are known to release gas and dust as they approach the sun, the reversal of a comet’s rotation is an unprecedented observation. The process is thought to be driven by the uneven release of gas and dust from the comet’s surface. As these materials are ejected, they create a torque that can alter the comet’s spin. In the case of 41P, the torque was strong enough to not only slow the rotation but to flip it completely.

The Hubble Space Telescope has also recently captured images of another comet, C/2025 K1 (ATLAS), as it disintegrated. The images, taken between November 8th and 10th, 2025, represent the first time Hubble has recorded such an event in its early stages. K1 fragmented into at least four distinct pieces, each exhibiting a visible coma. Ground-based telescopes were only able to detect a blurry light source at the time of the breakup, highlighting Hubble’s superior resolving power.

The disintegration of K1 occurred approximately one month after the comet reached perihelion – its closest approach to the sun – where This proves located about one-third the distance between Earth and the sun. Long-period comets, like K1, often begin to break apart after passing perihelion due to the intense heating and stress they experience. The fragments of K1 are currently about 400 million kilometers from Earth and may eventually be ejected from the solar system.

Researchers had previously attempted to observe cometary disintegration with Hubble, but were unsuccessful until this accidental observation of K1. The team originally intended to observe a different comet, but when that target became unavailable, they turned to K1, coinciding with its unexpected breakup.

Separately, the Hubble Space Telescope has been used in a project called “Hubble Search for Transition Comets,” which involves amateur astronomers in the search for OH radiation from asteroids that may have once been comets. This project is one of six research initiatives approved by NASA that allows amateur astronomers to participate in Hubble observations. The research focuses on asteroids with elliptical orbits, such as (944) Hidalgo and (2201) Alethe, which resemble those of comets.