Comet 41P/Tuttle-Giacobini-Kresák Mysteriously Reversed Spin, Astonishing Scientists

A comet, 41P/Tuttle-Giacobini-Kresák, has baffled astronomers by reversing its spin after passing the Sun in early 2017. This unprecedented event challenges existing understanding of cometary behavior and may offer clues about how smaller comets disintegrate.

What Happened?

As comet 41P/Tuttle-Giacobini-Kresák made its closest approach to the Sun (perihelion) in early 2017, its rotation dramatically slowed. Observations in March 2017 indicated a rotation period of approximately 20 hours. By May of the same year, this period had more than doubled to around 53 hours. Remarkably, by December 2017, the comet was rotating in the opposite direction, completing a rotation in just 14.4 hours. Astronomer David Jewitt of the University of California, Los Angeles, believes the comet likely stopped rotating altogether around June 2017 before reversing course.

Why is This Significant?

Changes in a comet’s spin are not uncommon as they approach the Sun. However, the speed and magnitude of the change observed in 41P are exceptional. Dennis Bodewits, an astronomer at the University of Maryland, noted that the previous record for a comet slowdown occurred with 103P/Hartley 2, which slowed from 17 to 19 hours over 90 days. In contrast, 41P experienced a more than tenfold change in just 60 days [ScienceAlert].

What Causes a Comet to Change Spin?

Comets are composed of loose collections of rock and ice. As they approach the Sun, they heat up and release gases and dust. These jets of material can act as thrusters, altering the comet’s spin. While these rotational changes are known to occur, the scale of the change in 41P is unusual. [Vice] suggests that the ice-thawing process can create jets strong enough to alter a comet’s spin.

What Does This Tell Us About Comets?

The behavior of 41P suggests that some comets may be more fragile than previously thought. Researchers hypothesize that the extreme spin changes could contribute to a comet’s disintegration. [UCLA Newsroom] reports that Jewitt believes the findings may assist explain how small comets ultimately break apart, potentially being “blown to bits by their own spin.” [The New York Times] also reported on this possibility.

Further Research

The unusual behavior of comet 41P/Tuttle-Giacobini-Kresák continues to be studied by astronomers, offering valuable insights into the dynamics of these icy bodies and the processes that govern their evolution.