Interplanetary Comets May Not Be That Rare After All

One of the most interesting discoveries in astronomy happened in 2019 when an interstellar comet was discovered in our solar system. The comet was called Borisov, and astronomers believe interstellar comets like it may not be rare after all. Recently, scientists calculated that there may be more objects from outside of our solar system in the Oort Cloud than objects born inside our solar system.

This week, a new study was published by researchers from the Center for Astrophysics | Harvard & Smithsonian that presented new calculations focusing on the Oort Cloud. That cloud is made up of debris and lies at the far edges of our solar system. Project researchers believe that inside the Oort Cloud is a significant number of interstellar objects.

Comet Borisov was very important to astronomers. Study researcher Amir Siraj said before Borisov, the first interstellar comet detected, scientists had no idea how many interstellar interlopers might be in our solar system. While the exact number is unknown, one theory suggested there were fewer interstellar visitors than there were objects made in our solar system.

Calculations the scientists made for their study now indicate there could be substantially more objects from outside the solar system than expected. They made calculations using data gathered from Borisov, but they point out the calculations do have uncertainties. However, even considering those uncertainties, the study found interstellar material outnumbers native material from the solar system within the Oort Cloud.

Certainly, one question the study raises is why we haven't been able to find other interstellar visitors if they are so numerous. Study researchers say that we simply don't have the technology to see them. Part of the reason we can't see them is the vast distance the Oort Cloud resides from the Sun. The cloud is between 200 billion and 100 trillion miles away, and objects within the Oort cloud don't produce their own light.