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In a First, Scientists Observe a Comet Reversing Its Spin: "Like Pushing a Merry-Go-Round"
Comet 41P's small 0.6-mile nucleus reversed its spin due to uneven outgassing jets, with models predicting rapid instability and possible fragmentation, researchers said.
- On Thursday, May 26, 2026, researchers published findings in The Astronomical Journal showing the Hubble Space Telescope observed Comet 41P/Tuttle-Giacobini-Kresák slowing and then reversing its rotation direction, a phenomenon never previously witnessed in a comet.
- Paper author David Jewitt of the University of California at Los Angeles explains that uneven outgassing jets acting like thrusters caused the spin reversal; the comet's small size, just 1 kilometer across, makes it susceptible to these torquing forces.
- Data from NASA's Neil Gehrels Swift Observatory in May 2017 showed the comet rotating once every 46 to 60 hours, while Hubble images from December 2017 detected the comet spinning much faster again, with a period of approximately 14 hours.
- Rapid rotation generates centrifugal forces that could overcome the object's weak gravity, leading Jewitt to expect the comet's nucleus will "very quickly self-destruct" as spin changes create structural instability.
- As a Jupiter-family comet, 41P has likely occupied its present orbit for roughly 1,500 years, visiting the inner solar system every 5.4 years after being flung from the Kuiper Belt by Jupiter's gravity.
19 Articles
19 Articles
A small comet can change the way it rotates. That’s what documented a study published in The Astronomical Journal about comet 41P/Tuttle–Giacobini–Kresak, whose core not only altered its rotational velocity, but probably reversed its direction of rotation after its closest passage to the Sun in 2017. The work, led by astronomer David Jewitt, analyzed observations from the Hubble space telescope taken eight months after the perihelion. Data shows…
In a first, researchers observe a comet reversing its spin: "Like pushing a merry-go-round"
Astronomers have found archival data showing a one-of-a-kind event where a spinning comet appeared to reverse the direction of its rotation, NASA said in a news release. The comet, named 41P/Tuttle-Giacobini-Kresák, originated in the outer solar system and visits the inner solar system every 5.4 years, NASA said. During a pass around the sun in 2017, its rotation dramatically slowed. A data comparison of its movements showed that in May 2017, it…
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