A 180 In Space: This Comet Stunned Scientists By Nearly Stopping Before Spinning Backwards

Last Updated:February 13, 2026, 19:29 IST

The reversal is thought to be the result of outgassing- when solar heating causes ice on the comet’s surface to sublimate into gas. T

Comet 41P/Tuttle-Giacobini-Kresak, a small icy body in our Solar System, has once again captured astronomers’ attention. Known for its bright flares and rare appearances near Earth, the comet stunned scientists when its rotation nearly stopped and then reversed direction, a phenomenon never observed at this scale before.

New analysis of Hubble Space Telescope images from December 2017, following the comet’s closest approach to the Sun, confirms this dramatic spin reversal. David Jewitt, an astronomer at the University of California, Los Angeles, who led the study, called it “not this big and so quick."

How Did Astronomers First Notice Something Unusual?

When 41P flew by Earth in April 2017, researchers observed its rotation slowing rapidly. Measurements from the Neil Gehrels Swift Observatory and ground-based telescopes revealed that the comet’s spin changed from completing a full rotation every 20 hours in March to 46 hours by May. By comparison, the previous record for a comet spindown was far milder: comet 103P/Hartley 2 slowed from 17 to 19 hours over 90 days.

What Caused Spin To Reverse?

The reversal is thought to be the result of outgassing- when solar heating causes ice on the comet’s surface to sublimate into gas. These jets of gas exert uneven torque on the nucleus, tiny though it may be, forcing it to slow and eventually spin in the opposite direction. David Jewitt’s lightcurve analysis confirmed that the nucleus, roughly 0.3 miles (0.5 kilometers) in radius, underwent this flip between April and December 2017.

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Why Does This Matter For Understanding Comets?

The findings shed light on the lifespans of small comets. Sub-kilometer comets like 41P are especially vulnerable to rapid changes in rotation caused by outgassing, which can ultimately destroy them. David Jewitt suggests that such spin instability may explain why fewer small comets are observed in the Solar System than models predict.

When Will We Get Another Chance To Study 41P?

Astronomers eagerly anticipate 41P’s next close approach to the Sun in 2028. Observing the comet again may reveal whether it has undergone another dramatic spin change, offering further insight into how small comets evolve and meet their ultimate fate in the Solar System.

News world A 180 In Space: This Comet Stunned Scientists By Nearly Stopping Before Spinning Backwards

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