When astronomers discovered the mysterious Oumuamua celestial body about two years ago, the excitement was intense: for the first time, they were able to watch an interstellar object fly through our solar system. Some even considered the cigar-shaped stone to be a probe or a spaceship from another world. The fact that the body was sent to us by a foreign civilization is now considered as excluded.
Somewhat conventional, the second interstellar celestial body in our vicinity obviously comes along, which science now knows. Discovered at the end of August by the Russian amateur astronomer Gennady Borisov, the comet 2I / Borisov is very similar to its relatives from our solar system. This is reported by researchers led by Piotr Guzik from the University of Krakow, Poland, in the journal Nature Astronomy.
One kilometer big, solid core
The team had taken pictures with the four-meter mirror of the William Herschel telescope on La Palma and the eight-meter mirror of the Gemini North Telescope in Hawaii. The evaluation showed that the comet's solid core is about one kilometer in size. The celestial body has a reddish hue and its surface consists mainly of dust.
"Based on the first characterizations, the object does not seem to be different from the comets that exist in our solar system," says researcher Guzik. But the orbit of comets reveals its origin from the depths of space.
In the video: How interstellar dust creates celestial bodies
This confirms initial investigations that attest that 2I / Borisov is related to comets from the solar system. This observation suggests that comets in other solar systems could form similar processes as in ours, so the conclusion of the astronomers involved.
According to the researchers, the comet is likely to gain in brightness in the coming weeks and months. This would improve the observation conditions even more. "We believe that the best is yet to come," says co-author Waclaw Waniak.
The team was able to secure further observation time on the Gemini North Telescope prior to the appearance of the interstellar comet, as well as on the Very Large Telescope of the European Southern Observatory in Chile. "We can say with certainty that this body will revolutionize planetary astronomy and become a milestone for astronomy in general," said Guzik.
2I / Borisov should reach his nearest-Earth point shortly after Christmas. Researchers now assume that in the future similar objects from areas beyond the solar system could be observed once a year. Important aids are algorithms that automatically search telescope observation data for clues to such visitors from the depths of space. They also helped Guzik and his colleagues.
For a while, researchers also had celestial bodies Oumuamua for a comet. But one had to say goodbye to this idea because no tail or coma was observed. To date, the classification of Oumuamua is not readily possible, it was an object so unseen.