Overview
- The Astronomical Journal published the peer‑reviewed analysis Thursday, using reanalyzed Hubble archival images to confirm that comet 41P/Tuttle–Giacobini–Kresák flipped its spin.
- Observations in 2017 show a clear sequence: after a March rotation measured from the ground, Swift data in May slowed to 46–60 hours, then Hubble in December found about 14 hours, which implies a reversal.
- Scientists say jets of gas venting from sun‑warmed ice acted like tiny thrusters on the small nucleus, making it easy to slow and then reverse the comet’s spin.
- Modeling based on the measured torques and mass loss indicates the nucleus could become unstable if future spin‑ups continue, raising the risk of fragmentation.
- The study also finds the comet’s gas output in 2017 was about one‑tenth of its 2001 level, pointing to fast surface changes rarely seen on human timescales.