At the end of August the amateur astronomer Gennady Borisov might have looked quite excited through his telescope. With the self-built 65 centimeters in diameter, he had discovered something very interesting in space from the Crimea: An object moved at a relatively high speed towards the sun.
Borisov reported his observation. Quickly, the object had aroused the interest of astronomers around the world. Because his trajectory indicated that it is an interstellar guest who crosses our solar system and leads him out of our system. To test that, the researchers needed more data. That was not easy, because due to its proximity to the sun and the brightness, the comet, only 16 kilometers in diameter, could only be observed for one to two hours per night.
But now astronomers of different observatories are sure: It is not just an unknown comet, but the object actually does not come from our solar system. Thus, according to the International Astronomical Union (IAU) in honor of its discoverer, 2I / Borisov, according to 1I / 'Oumuamua of 2017, is only the second interstellar object that was sighted during a flight through our solar system.
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Borisov offers astronomers a rare chance to gain insight into a strange solar system before disappearing into the depths of space again. Researchers at the Astrophysical Institute of the Canaries (IAC) have already obtained a first so-called spectrum of the interstellar wingtip, which comes from the direction of the constellation Cassiopeia, which provides a kind of fingerprint of its chemical composition.
"The spectrum of this object is similar to that of the comets of our solar system, and this indicates that their composition must be similar," said IAC researcher Julia de León. This observation suggests that comets in other solar systems could form similar processes as ours, "added de León colleague Javier Licandro. Apparently, Borisov also consists of a mixture of rocks, ice and dust.
"The comet's current velocity is high, about 150,000 kilometers per hour, which is well above the typical speeds of objects orbiting the Sun at that distance," says Davide Farnocchia of the US space agency Nasa, according to a statement.
In video: Trajectory of Oumuamua
NASA
Probably on the 8th of December, Borisov will be closest to the sun and will pass it at twice the Earth's distance. He is not in a closed orbit around the sun but is on a so-called hyperbolic path on the way. That is, his straight line direction is deflected by the gravity of the sun - he flies in about a hyperbola.
"The object will reach its maximum brightness in mid-December and then be seen by mid-April with medium-sized telescopes," explained Farnocchia. "After that, until October 2020, it will only be observable with larger, professional telescopes."
A little later in December, the object is 300 million kilometers from Earth. But it will not come closer to our planet.