Artist’s Impression of Comet 41P Approaching the Sun.
Credit: NASA, ESA, CSA, Ralph Crawford (STScI)
A recently observed small comet has made history by changing its rotation direction, a first for astronomers. This intriguing phenomenon provides insights into the comet’s interior, potentially illuminating the composition of the early solar system.
Known as Comet 41P/Tuttle-Jacobini-Krezak or simply 41P, this comet spans about 1 kilometer in diameter and completes an orbit around the Sun approximately every 5.4 years. It becomes visible as it approaches the inner solar system, with its last appearance recorded in 2017.
In March 2017, Comet 41P was observed spinning roughly every 20 hours. However, astronomers noted a significant deceleration by May, with a rotation period extending to between 46 to 60 hours. A team led by David Jewitt from the University of California, Los Angeles, analyzed Hubble Space Telescope data from December 2017 and discovered that the comet’s rotation has accelerated again, now completing a rotation roughly every 14 hours.
The prevailing theory suggests that the comet’s rotation slowed to a halt, at which point it began rotating in the opposite direction. This dramatic shift is attributed to sunlight sublimating ice on its surface, transforming it into gas that behaves like a jet. If this jet propels in the opposite direction, it can decelerate the comet and eventually reverse its rotation.
“This is the first documented instance of a rapid change in the rotation direction of a celestial object,” asserts Dmitri Vavilov, a researcher at the University of Washington in Seattle. Typically, substantial changes in celestial body rotations, even for a small comet like 41P, span decades or centuries.
“Tracking 41P’s next appearance from late 2027 to early 2028 will be fascinating,” says John Noonan from Auburn University in Alabama. “Our goal is to determine whether these comets risk destruction due to rotational stress.” If Comet 41P spins too rapidly, it risks disintegrating.
“This comet’s core is anticipated to self-destruct shortly,” explains Jewitt in a recent statement. In fact, such disintegration might already be occurring. This event could present a remarkable opportunity to examine the inner composition of comets that have remained unchanged since the solar system’s formation, yielding critical insights into the early solar system’s chemical landscape.
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Source: www.newscientist.com
