Jakarta –
Astronomers discovered that Comet 41P/Tuttle-Giacobini-Kresák, a small comet in the Solar System, underwent a dramatic change in rotation direction after approaching the Sun. This phenomenon is rare and has never been seen at this level of change in scientific journals.
New analysis of Hubble Space Telescope images from 2017 shows that the rotation of the comet’s nucleus undergoes significant changes during the period of passing perihelion (the closest point to the Sun).
At the start of the observations, the comet was spun by outgassing forces, the push of gas that escapes when ice on the surface evaporates, causing its rotation period to lengthen from about 20 hours to more than 53 hours in a few months.
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Then, data from December 2017 revealed something even stranger: the comet’s rotation appeared to not only slow down, but stop completely and then reverse direction, rotating again with a period of about 14.4 hours, much faster but in the opposite direction.
According to Dr. David Jewitt, an astronomer from the University of California, Los Angeles (UCLA), this change is the effect of the uneven pushing force of gas jets that come out of the comet’s surface as it approaches the Sun.
“The observed rotational changes are a natural consequence of the torque caused by volatiles escaping from this small nucleus,” said Jewitt, quoted from IFL Science.
This change in rotation can actually be interpreted as a result of anisotropic outgassing, namely an uneven jet of gas from the comet’s surface that functions like a mini ‘nozzle’ that provides impetus to the comet’s body. When a comet approaches the Sun, its icy surface heats up and turns directly into gas (sublimation), creating pressure that can slow down and then reverse the direction of rotation.
Comet 41P/Tuttle-Giacobini-Kresák has a very small nucleus, only about 500 meters across. Therefore, the force from these gas jets can have a large impact on their rotation compared to larger objects.
This phenomenon provides scientists with important insights into the dynamics of cometary bodies, in particular how torsion reactions from sublimation can affect the rotation of small objects in space. Rotational changes also suggest that small comets may be deforming or even breaking up due to stresses generated by unstable rotating motion.
The comet is expected to approach the Sun again in 2028, providing an opportunity for new observatories such as the Vera C. Rubin Observatory to further study this unique rotation phenomenon and understand whether this behavior is common or a rare case.
(rns/rns)
