We now turn our attention to space objects with an update on the interstellar comet 2I/Borisov. Back in the before times, in fall 2019, amateur astronomer Gennady Borisov discovered a comet passing through our solar system on a trajectory that indicated it is a visitor from some other star system. Since then, astronomers have used every possible telescope to observe Borisov in as much detail as possible.

According to Ludmilla Kolokolova: The arrival of 2I/Borisov from interstellar space represented the first opportunity to study the composition of a comet from another planetary system and check if the material that comes from this comet is somehow different from our native variety. 

One of the involved telescopes, the giant Very Large Telescope in Chile, has revealed that Borisov appears to have received minimal weathering from solar wind and radiation and preserves the composition it was formed with. According to study lead author Stefano Bagnulo: 2I/Borisov could represent the first truly pristine comet ever observed. 

This work appears in Nature Communications. Coauthor Alberto Cellino adds: The environment in which 2I/Borisov originated is not so different in composition from the environment in the early Solar System. 

Currently, Comet Borisov is racing out of our solar system and is beyond the ability of a spacecraft to readily run down and sample or observe. In anticipation of future discoveries of alien comets, the European Space Agency is planning to launch Comet Interceptor in 2029, which will have the capability of reaching another visiting interstellar object, if one on a suitable trajectory is discovered.

More Information

ESO press release

“Unusual polarimetric properties for interstellar comet 2I/Borisov,” S. Bagnulo et al., 2021 March 30, Nature Communications