Astronomers from Universidade to Califórnia in Los Angeles (UCLA) have documented rare dynamic behavior in a celestial body that crosses the inner Sistema Solar. The object, identified as comet 41P/Tuttle-Giacobini-Kresak, presented a drastic physical change during its trajectory: the icy body slowed down its rotation movement until it reached an apparent stop state, and then began to rotate in the opposite direction. The analysis points out that this phenomenon, which challenges the expected mechanical stability, was driven by an intense gas release activity on its surface.
The conclusions were based on data collected by Telescópio Espacial Hubble, whose high-precision instruments monitored the light variations and structure of the comet’s nucleus during its close pass to Sol in 2017. The research, led by planetary scientist David Jewitt, offers new understanding about the volatility of small celestial bodies and how thermal interaction with the central star can fundamentally alter the physics of these objects.
The study not only records a singular event, but provides key pieces to solving long-standing questions in astronomy, specifically about the lifespan and disintegration of smaller comets. The data suggests that rotational instability acts as a natural self-destruction mechanism, shaping the population of objects orbiting Sol.
Dramatic change in turning speed
Comet 41P, a member of the Júpiter family of comets, has a typical composition of ice, dust and rocks, remnants of the formation of the planetary system. When approaching perihelion, solar heat causes the sublimation of surface ice, transforming it directly into gas. Esse process generates the visible coma, but also exerts considerable mechanical forces on the solid core.
The monitoring carried out revealed a sequence of events that impressed the scientific community due to the speed and magnitude of the physical changes:
– In March 2017, the comet completed a rotation on its own axis every 20 hours.
– In May of the same year, this period extended to 46 hours, indicating a massive slowdown.
– In December, after a period in which the object was unobservable, it reappeared rotating every 14 hours, but in the opposite direction.
The most plausible physical interpretation for this sequence is that, after the month of May, the comet continued to lose angular velocity until it reached a point of zero rotation. Imediatamente after this stop, the forces acting on the surface began a reverse movement, accelerating the rotation in the opposite direction very quickly.
The effect of gas jets
The mechanics behind this reversal lie in the active nature of the cometary surface. Quando the ice sublimates, it is expelled in the form of high-speed jets of gas. If the emission were uniform throughout the sphere, the forces would cancel each other out. However, 41P’s surface is irregular and the jets are emitted asymmetrically, functioning as thrusters located at random points in the nucleus.
These “natural motors” exert a torque on the comet’s body. Dependendo Due to the orientation and power of these jets, they can both accelerate the object’s rotation and act as extremely powerful brakes. In the case of 41P, the configuration of the jets during the 2017 solar approach initially acted against the existing rotational motion.
The intensity of this braking was enough to overcome the rotational inertia of an object more than a kilometer in diameter in a matter of weeks. Isso demonstrates the violence of the degassing processes that occur when these icy bodies penetrate the hottest regions of Sistema Solar.
Natural selection in space
The observations have profound implications for understanding comet demography. Astrônomos have long noted a shortage of small comets, with nuclei smaller than a kilometer or two in diameter. Essa statistical gap suggested that some process destroyed these objects more quickly than the models predicted.
The behavior of 41P provides the observational evidence necessary to validate the rotational disintegration theory. If gas jets can alter the rotation so drastically, they could easily accelerate a comet until the centrifugal force overcomes the weak gravity holding the nucleus together. Nesse scenario, the comet would fragment, scattering its pieces across space or turning into a cloud of dust and debris.
David Jewitt and his team propose that this mechanism is the main cause of the premature “death” of small comets. Rotational instability therefore works like an evolutionary filter, eliminating smaller and less dense bodies, leaving behind only larger nuclei or those with more cohesive internal structures.
Technology and future observations
The astronomical community eagerly awaits the next approach of comet 41P, scheduled for the beginning of 2028. With the advancement of monitoring technologies, it will be possible to verify whether the pattern of instability continues or whether the configuration of the jets has changed.
For these future observations, scientists will have the support of new instruments, including the Observatório Vera C. Rubin, on the Chile. With its wide-sky scanning capability, the observatory will make it possible to monitor not just 41P, but thousands of other small bodies for signs of similar rotational changes.
The 41P study reinforces that Sistema Solar is a dynamic and constantly changing environment. The ability to observe these changes in real time, such as the stopping and reversing of an entire world, highlights the power of modern observational tools and the physical complexity that governs the smallest inhabitants of our cosmic neighborhood.
