Overview
- A February 2026 arXiv study by UCLA’s David Jewitt reanalyzing December 2017 Hubble images concludes Comet 41P very likely reversed its rotation following its 2017 perihelion passage.
- Swift and ground-based observations showed the spin decelerating from about 20 hours in March 2017 to roughly 46 hours by May, with Hubble indicating a ~14-hour rotation in December consistent with an opposite direction.
- The analysis estimates a nucleus radius of about 0.3 miles (0.5 kilometers), implying low rotational inertia that makes the comet highly susceptible to torque.
- Researchers identify anisotropic outgassing as the most plausible driver of the rapid spindown and flip, with astronomers describing this as the first direct observation of a full spin reversal in a comet.
- Scientists plan targeted observations during 41P’s next favorable return in early 2028, including surveys by the Vera C. Rubin Observatory to test these conclusions and monitor further evolution.