Observations with NASA's infrared telescope have confirmed that the unusual black mark on Jupiter is the trail of the impact of a comet swallowed by the giant planet. The discovery was again helped by a fortunate coincidence
For luck
A strange dark spot on Monday night was noticed by astronomy lover Anthony Wesley, who lives near the Australian capital Canberra. Wesley has indisputable authority in the matter of amateur observations of Jupiter and more than a year ago he already managed to become the author of an important discovery - he was the first to notice a new red spot that formed on the planet in the spring of last year.
This time Wesley almost missed his luck - by his own admission, after two hours at the telescope, he was about to finish his observations. However, at the last moment, the astronomer decided to sit at the monitor on which photographs of Jupiter are broadcast for another half hour - and 15 minutes later, an incomprehensible dark mark began to creep out from behind the planet's disk. After following the giant planet for another half hour, Wesley went to write messages on the Internet forums of amateur astronomers and e-mails to the addresses of professional astronomers.
Among the professionals whose addresses were in Wesley's notebook was Glenn Orton of NASA's Jet Propulsion Laboratory. Once again, everything turned out so well that Orton and his colleague Leigh Fletcher had just scheduled IRTF observations of Jupiter last Hawaiian night (Monday afternoon Moscow time). It was not necessary to beg colleagues and the observatory authorities to give up time, and scientists received images of Jupiter in the infrared range.
Accurate strike
Although the new spot is not at all like all meteorological formations observed on Jupiter so far, before the observations of Orton and Fletcher, there was still the possibility that the black mark was some kind of previously unknown type of especially dark vortices. After infrared images, this possibility disappeared - the data shows all the signs of a cosmic impact. The last time something like this was observed 15 years ago, when two dozen fragments of comet Shoemaker-Levy 9 crashed into Jupiter one after another.
The image taken at 1.65 microns shows a bright hot spot at the impact site and a slightly less bright but highly visible halo slightly away from the main mark. According to scientists, the hot spot itself is a consequence of the heating of the atmosphere of Jupiter at the place of the collision with a space alien, and the halo is a substance that is raised upon impact above the main cloud layer of the planet and heated by the rays of the Sun.
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Stinking comet
It is still impossible to say which celestial body Jupiter swallowed - scientists are still processing the data obtained. But there are some hints of the physical nature of the alien. According to the British popular science magazine New Scientist, Orton and Fletcher noticed signs of increased ammonia at the impact site. This leads scientists to speculate that Jupiter was struck by a comet that contained a lot of frozen gases, rather than a solid rocky asteroid.
As for the size of this comet, it is still impossible to estimate it. The size of the spot itself is about the size of the Earth. Fragments of the nucleus of comet Shoemaker-Levy-9, the size of which is estimated at several hundred meters, left approximately the same marks. Nevertheless, the size of the spot should depend on both the relative velocity of the impact and the physical properties of the body colliding with Jupiter, which are still unknown. Professional scientists are now continuing their observations and even hope to knock out the observing time from NASA on the Hubble Space Telescope to get a high-quality image of Jupiter.
Pictures of Wesley (the south pole of the planet in these frames is at the top). A general view of Jupiter (a dark spot is clearly visible in the upper part) and a larger increase in the impact area (in color), in which three faint accompanying spots can be discerned, possibly remaining after the fall of smaller body fragments. Between the two total frames - 50 minutes, you can see how the impact mark shifted as the planet rotated.
Bottom: 1994 impact marks (for comparison), ultraviolet and visible (photo by Anthony Wesley, Hubble Space Telescope Comet Team / NASA).
The blows became frequent
However, from one circumstance, astronomers are already feeling a little uncomfortable - it seems that cosmic impacts happen a little more often than astronomers expected. The literature with estimates of this frequency is controversial, but most experts believed that such impacts should occur no more than once every several thousand, at least hundreds of years. Only a decade and a half have passed since the previous strike.
The impact of such a comet on the Earth at a speed typical of the Earth's surroundings would lead to an explosion with a yield of hundreds of megatons in TNT equivalent and a crater with a diameter of kilometers. All these results, of course, depend on the specific parameters of the strike - you can play with them on the space strike simulator. Fortunately, even an overestimation of the frequency of impacts on Jupiter cannot directly affect the estimate of the frequency of such events on Earth - the space populations bombarding these two planets are too different.