Are we in a cosmic melting pot? Most of the comets in our solar system could have come from alien stars, scientists say

Are we living in a cosmic melting pot? A new study published today in the Monthly notices from the Royal Astronomical Society suggests that most of the comets in our solar system originally came from extraterrestrial star systems.

Research also suggests that some asteroids in the inner solar system may also have interstellar origins.

These are the latest theories in an incredible new chapter in astronomy that began on August 30, 2019 when Crimean amateur astronomer Gennady Borisov discovered Comet 2I / Borisov, a giant snowball whose speed and trajectory indicated that it came from beyond our Sun. System.

This first observation of an interstellar comet passed the Earth at 110,000 miles per hour. The Hubble Space Telescope captured it in October and it was gone by mid-2020, but “Comet Borisov” forever changed astronomy.

“Before the detection of the first interstellar comet, we had no idea how many interstellar objects were in our solar system, but the theory about the formation of planetary systems suggests there should be fewer visitors than permanent residents. “said Amir Siraj, lead author of the study a concurrent undergraduate and graduate student in Harvard’s Department of Astronomy. “Now we are seeing that there could be a lot more visitors. “

The article includes new calculations which show that there are more interstellar objects than objects belonging to our solar system, but only in the Oort cloud. The Oort Cloud is a spherical shell of icy objects extending over an area between 200 and 100,000 billion kilometers from our Sun. It is believed to be made up of debris left over from the formation of the solar system.

The Oort Cloud is a reservoir of long-lived comets that fall at some point in the inner solar system, where we observe them. However, this article suggests that such native comets could be outnumbered 10 to 1 in the Oort cloud by interstellar comets.

So why don’t we see more interstellar comets?

• We can only see comets near Earth, where gravity means native comets are much more likely to enter.
• We lack the technology to see objects in the Oort Cloud because, unlike stars, objects far from the Sun do not produce their own light. That could change with the Transneptunian Automated Occultation Investigation later in 2021 and the opening of the Vera C. Rubin Observatory Sky Investigation in 2022.

However, there could also be implications for objects much closer to us than the distant Oort Cloud.

“These results suggest that the abundances of interstellar objects and Oort clouds are comparable closer to the Sun than to Saturn,” said Matthew Holman, astrophysicist and former director of CfA’s Minor Planet Center, which tracks comets, asteroids and other debris in the Sun. System. “When you look at the data on the asteroids in this region, the question is: are there any asteroids that are truly interstellar that we just didn’t recognize before?”

Some asteroids are detected but are not observed or tracked every year, so we lack data on them. Could they have interstellar origins? If the Oort Cloud is truly dominated by interstellar objects, there must be more debris from the formation of planetary systems than previously thought. “Studying interstellar objects could help us unlock the secrets of how our planetary system – and others – formed,” Siraj said.

The study was funded in part by a grant from the Breakthrough Prize Foundation, which supports scientists and mathematicians working on some of the most important and fundamental questions in their fields.

I wish you clear skies and big eyes.