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Scientists have discovered a comet traveling one way out of the solar system after a close encounter with Saturn.
The comet, named Comet A117uUD (A117uUD), was only discovered on June 14, 2024, by the Asteroid Impact Terrestrial Alert System (ATLAS). However, the researchers were able to use 142 observations of the comet to “wind back” its orbit around the sun. This showed that A117uUD collided with Saturn, the second largest planet in the solar system, famous for its bright and distinctive rings, in 2022 and was changed forever.
The encounter with the gas giant put the comet on an extremely flattened or elliptical orbit that will send it out into interstellar space beyond the influence of the sun. Using models to fast-forward A117uUD’s path, the team found that it will exit the solar system at a speed of about 6,710 miles per hour (10,800 km/h). That’s about four and a half times the top speed of the Lockheed Martin F-16 jet fighter.
This is only the second solar system comet we’ve seen leaving the solar system. The first was Comet C/1980 E1 (Bowell), which was placed on an escape path from the solar system by an encounter with Jupiter on December 9, 1980.
“Our results show that the case of comet A117uUD is similar to that of C/1980 E1 (Bowell), making it possible for A117uUD to have an extrasolar origin,” the team behind the research wrote in a paper published in the journal AAS Research Notes . “The fact that two ejections were observed after a planetary encounter in less than 45 years suggests that such events are relatively frequent.”
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Make up your mind. Are you coming or going?
It was not always clear that A117uUD was a solar system body destined to leave its home planetary system. When the team behind this discovery first analyzed the icy space rock, they thought its hyperbolic orbit might indicate it was an intruder into our solar system.
The first solar system object discovered by mankind was the odd cigar-shaped asteroid 1I/’Oumuamua (‘Oumuamua), which is a Hawaiian word that roughly translates as “a messenger from far away who came first. “
When it was discovered in 2017, ‘Oumuamua immediately stood out to astronomers because of its very unusual shape and because it had no Coma (the halo that surrounds a comet), nor a distinctive cometary tail despite appearing to be a hybrid it’s a strange comet/asteroid. . It was also accelerating away from the sun, leading to the now (largely) dismissed claim that this visitor from another planetary system could be an alien spacecraft.
The solution to these unique features was to roast ‘Oumuamua with cosmic radiation before it reached the solar system, causing hydrogen to form and become trapped within its body. That hydrogen was released and began to spray out of the space rock when Oumuamua reached the relative heat of our planetary system, which drove it.
‘Oumuamua is now out beyond Neptune’s orbit, passing through the Kuiper Belt, a ring of icy bodies near the outer edge of the solar system. Not only is it beyond the reach of our telescopes, but the interstellar medium will never come back toward Earth or the sun.
‘Oumuamua isn’t the only interstellar intruder we’ve seen entering the solar system, however. Comet 2I/Borisov (2I/Borisov) was the second confirmed interstellar body and the first confirmed interstellar comet found within the solar system.
Crimean amateur astronomer Gennady Borisov 2I/Borisov was discovered on August 30, 2019. This solar system intruder really put A117uUD’s speed to shame, racing through the solar system at a hair-raising 110,000 mph. That’s 150 times the speed of sound, and leaves a Lockheed Martin F-16 in its trail of dust, traveling 75 times as fast as the jet fighter’s top speed.
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Like ‘Oumuamua, 2I/Borisov was just passing through, briefly interesting astronomers and the general public alike, as it headed for a way out of the solar system, never to return.
The encounter between A117uUD and Saturn affected the comet’s orbit to such an extent that the team could not reconstruct it before the meeting, but they did enough to assure themselves that this was not a third extrasolar interloper.
Perhaps one day, the comet A117uUD launched from Saturn will attract astronomers from some distant alien civilization, perhaps billions of years after its discoverers on Earth have passed away.