Los angeles: Astronomers tracking the movements of Comet 41P/Tuttle-Giacobini-Kresak have found that it appears to have slowed its rotation, before the direction of its rotation reversed. Comet 41P/Tuttle-Giacobini-Kres¡k, a small icy body about 0.6 miles across, displayed this unusual behaviour as it approached the sun in 2017.
According to Emirates News Agency, David Jewitt, an astronomer at the University of California, Los Angeles, used images taken by the Hubble Space Telescope in 2017 to study this comet. Like planets, moons, and asteroids, comets spin naturally, and astronomers had already seen that 41P's spin was slowing substantially before Hubble's observations revealed it was spinning in the opposite direction.
Dr. Jewitt, who published his findings on the arXiv website ahead of publication in The Astronomical Journal, noted that the magnitude and speed of change in the comet's spin were unprecedented. Comets, which are chunks of rock and ice from the outer solar system, occasionally enter the inner solar system, where they heat up and their ice sublimates, sometimes producing visible tails.
Dennis Bodewits, an astronomer at Auburn University, explained that some comets experience more significant events where material is ejected from the surface in a manner similar to a rocket-like jet, altering the comet's spin. This process is occurring on Comet 41P but in a more extreme form.
As Comet 41P approached the sun in 2017, Dr. Bodewits and his colleagues used NASA's Swift telescope to observe the comet. Although the surface was not visible, changes in brightness as the comet spun were monitored, revealing a dramatic change in its rotation period from 20 hours to 46 hours between March and May 2017.
No further observations were possible until December 2017 due to the comet's proximity to the sun. When it became visible again, Hubble's images showed the comet's spin had increased again to approximately every 14 hours. This suggested the comet had stopped and reversed its spin direction between May and December 2017.
The findings are significant as smaller comets like Comet 41P are less common than expected in the solar system. One hypothesis is that jets on these comets may cause them to spin until they disintegrate. Dr. Jewitt suggested that rotation might be a destructive process for comets, explaining their shorter-than-expected lifespans.
Comet 41P is expected to pass close to the sun again in early 2028.
