Weird comet from another star system just spotted

On August 30, in the morning asleep, a Ukrainian amateur astronomer named Gennady Borisov spotted a strange comet hovering through our solar system. Now, astronomers have tentatively verified that the object, named C / 2019 Q4 (Borisov), was moving too fast for it to be captured by the gravity of the sun, a sign that it was probably an interstellar intruder .

If these results persist, the T4 C / 2019 would be only the second visitor to another stellar system ever detected, after the discovery in 2017 of the enigmatic space rock known as 'Oumuamua' . Although its origins are not yet completely certain, the C / 2019 Q4 is a confirmed comet. Astronomers have already detected that the object – which is probably several miles away – has a coma, a blurred sheath of dust and gas that forms when sunlight warms the icy surface of a comet.

This means that scientists will be able to collect much more data on its composition than for Oumuamua. On the one hand, the fourth quarter of C / 2019 is bigger and brighter, which offers more opportunities to study its light and discover chemical cues. In addition, astronomers have discovered "Oumuamua only when it comes out of the solar system – but C / 2019 Q4 is still in. It will be closest to the sun on December 7th, and closest to Earth, within a radius of 180 million kilometers, on December 29th.

"This is the first very active object we have seen coming from something that has formed around another star," says Michele Bannister, astronomer at Queen's University in Belfast. Bannister adds that C / 2019's fourth quarter observations can not be seriously considered until mid-October, because of its position relative to the blinding sun. But for months, astronomers will look up at the sky to get what might be their best look at an interstellar visitor.

"What's really fantastic is that this thing can be observed for a year," says Matthew Holman, Acting Director of the Minor Planet Center of the International Astronomical Union, which published the verification of the path of the C / 2019 Q4 in space, Wednesday night.

"We can see a little bit of another solar system," he adds, "and without necessarily knowing what system it comes from, it's exciting."

Borisov, a former comet hunter, discovered C / 2019 Q4 by focusing his observations on the Crimean astrophysical observatory on the northeastern horizon, in a near-sky corner. of the constellation Gemini. Astronomers tend to avoid looking in these "bright" areas of the sky near the horizon, as they are difficult to see and can damage the sensitive optics of the telescopes.

The first reports on Borisov's discovery made waves among astronomers. Quanzhi Ye, of the University of Maryland, learned of Comet's existence on Sunday, after a colleague commented on the bizarre orbital track of the subject in a group e-mail. You also noticed that Scout, a comet and asteroid tracking service run by NASA's Jet Propulsion Laboratory, relentlessly calculated that the object did not seem to have a circular or elliptical orbit.

In particular, Ye became fascinated by one of the orbital parameters of the comet: its eccentricity. If the eccentricity of an orbit is zero, the object draws a perfect circle around its star. The more the orbit is elongated and narrow, the more the eccentricity approaches it. If an object of our solar system has an eccentricity greater than one, it means that it has an arcuate trajectory and makes a punctual visit. The Minor Planet Center claims that the eccentricity of C / 2019 T4 exceeds three.

According to Ye, it is unlikely that C / 2019 Q4 is a comet that formed on the periphery of the solar system and was dragged into a flight path. To get this kind of shock, a comet should approach an object big enough to change its course, like a planet. But to the knowledge of astronomers, the C / 2019 T4 could not get closer to such usurpers of our solar system. The orbits of the planets around the sun are more or less aligned in the same plane, but the C / 2019 Q4 seems to dive the solar system at an angle of 44 degrees.

"That's why we say gravitational disturbances are almost impossible," says Ye.

Astronomers estimate that at some point there is an interstellar comet or asteroid somewhere in the orbit of Mars and about 10,000 in Neptune's orbit – but these objects are tiny and extremely weak, which makes them almost impossible to see.

"Oumuamua, the first interstellar visitor detected in our solar system, exploded in the fall of 2017. Astronomers did not spot this strange object until it was coming out of the solar system. He was flying at 98,000 kilometers an hour. But in the short time they had, enthusiastic scientists around the world turned their telescopes to the object and they learned a surprising amount about this cosmic debris. (Learn more about 'Oumuamua and what makes it so strange.)

While the distant object only looked like an infiltration of light in the best telescopes, its intense darkening and brightening every few hours seemed to suggest that he was lying down and that he rocked from one end to the other while he was zipping into our solar system. Astronomers estimate that the object measured between 590 feet and a quarter of a mile long but only up to 130 feet wide, giving the rocky body a pencil-like appearance.

Even more curious, "Oumuamua did not keep running at the same pace. After turning around the sun in early 2018, it accelerated unexpectedly. Speculation immediately turned around the cause. Harvard Professors Shmuel Bialy and Abraham Loeb presented an idea from another world: it may have been a spaceship using a solar sail sent by an extraterrestrial civilization.

There is almost certainly a more mundane explanation, though. According to other research, holes on the surface of the object could have emitted gas jets that would accentuate it, causing a cometary activity too low for our telescopes to see. Or, &umuamua could have been a globe of porous ice light enough for sunlight to give it a helping hand.

"Oumuamua has left many mysteries that may never be solved. That's why the prospect of studying the fourth quarter of C / 2019 with even more details has delighted astronomers. When asked by email what he did about the Minor Planet Center audit, Ye replied, "It's time to take telescopes !!!"