Astronomers at the Smithsonian Institution and Harvard (USA) have shown that the Oort Cloud contains more interstellar objects than celestial bodies originated in the solar system. This is reported in an article published in the Monthly Notices of the Royal Astronomical Society: Letters.
The theory of the formation of planetary systems suggests that there should be fewer alien objects than objects originally located in the Oort Cloud. However, the very fact of the discovery of the interstellar comet 2I / Borisov shows that the number of interstellar celestial bodies should be much greater at a considerable distance from the Sun, while in the immediate vicinity of it, the mass of objects formed from local matter prevails. This hypothesis can be tested with surveys of stellar shading by bodies in the Oort cloud, such as TAOS II (Transneptunian Automated Occultation Survey), specially designed to detect comets in the far reaches of the solar system.
Astronomers have carried out calculations of the estimated proportion of interstellar objects with large assumptions, but even with this in mind, they should prevail over comets and asteroids that originated in the solar system. Scientists expect the launch and follow-up of the Vera Rubin Observatory in 2022 to find more interstellar objects.
The Oort cloud is a hypothetical region of the solar system that is the source of long-period comets. It is assumed that the outer boundaries of the Cloud are located at a distance of 50-100 thousand astronomical units from the Sun (an astronomical unit is equal to the average distance from the Sun to the Earth), which approximately corresponds to 1-2 light years.
2I / Borisov is an object 20 kilometers in diameter, discovered on August 30, 2019. Observations have shown that the comet is moving in a hyperbolic orbit, that is, it has arrived from interstellar space and is not gravitationally bound to the Sun.