3I/ATLAS: Our Interstellar Visitor

For centuries, the night sky has sparked wonder in the hearts of humankind. Rather it be ancient star watchers drawing constellations in the sky to academics rigorously studying the cosmos with advanced technology, the stars, planets, and galaxies that reveal themselves when the lights go out have always been of great interest. Recently, these fixtures of the night sky have been joined by a new visitor; 3I/ATLAS, an interstellar comet.

3I/ATLAS was first discovered on July 1, 2025 by a telescope in Chile ran by the Asteroid Terrestrial-impact Last Alert System (ATLAS), a program developed by the University of Hawaii and funded by NASA, during one of it’s many automatic scans of the night sky. After this initial discovery, the records of ATLAS and other astronomy organizations were combed to find other images of the comet. Through this effort, records of the comet have been found all the way back in June 14.

The vast majority of comets that people have seen and interacted with originate from within our Solar System. Specifically, these comets typically originate from a region on the outskirts of the Solar System known as the Oort Cloud, a spherical cloud of icy remnants of the formation of our Solar System. According to the European Space Agency, this cloud is to far from Earth to have ever been observed directly.

3I/ATLAS, however, is different. 3I/ATLAS is what’s known as an interstellar comet. This means that the comet originates from outside of our Solar System. According to NASA, we know of it’s extrasolar origin from it’s orbital path. Unlike normal comets, whose trajectories can be traced as a complete orbit around our sun, 3I/ATLAS has a hyperbolic orbit. This means that it’s path can be represented as a line that gets curved by our sun’s gravitational pull.

This status as an interstellar comet makes 3I/ATLAS very interesting for researchers. This is largely due to the extremely rare nature of these types of celestial bodies, with 3I/ATLAS is only the third interstellar object to have ever been found passing through the Solar System. This, in part, is due to the difficulty involved in detecting such objects. According to David DeBruyn, Curator-emeritus of the Roger B. Chaffee Planetarium and former member of the board of the Grand Rapids Amateur Astronomical Association, “…these things have probably been flying through the Solar System for a very long time, and it’s not that unusual. It’s just that now we have the instrumentation and the survey techniques to pick them up.”

This interest has motivated researchers, such as those at NASA, to devote attention to studying the comet before it leaves. This can be seen in the variety of telescopic tools and observatories that have turned to view 3I/ATLAS, such as the James Webb Telescope, the Perseverance Rover, and the Psyche spacecraft. The images have revealed multiple facts about 3I/ATLAS. One particular topic of interest is the composition of the comet. According to Dr. Lauren Woolsey, a professor of astronomy at Grand Rapids Community Collage, “… the chemical makeup, so what elements are present and how much of each of those elements, is going to be slightly different than our Solar System because it formed from a collection of material that would be very similar to but not identical to our Solar System. Often, when we’re studying comets or asteroids; anything that we’ve sent small satellites to orbit or land on, they are object that we know formed with our Solar System and they’re giving us clues about our Solar System’s past and the chemical makeup of it. This one is different because it formed in a slightly different area, so a slightly different cloud of gas and dust.”

She goes on to elaborate, “…it’s giving us a sense of being able to compare and contrast our Solar System and rather it is a standard assortment of elements or if there is anything unique to either our Solar System or unique to this particular object.” One notable feature found in this regard is heightened levels of diatomic carbon (C2). This particular type of carbon contributes to a signature green color of the comet when heated. DeBruyn also noted that 3I/ATLAS is rich in substances like carbon monoxide, unlike comets from our solar system, which are chiefly made of ice.

One misconception that both Dr.Woolsey and Mr. DeBruyn made a point of discouraging is speculation about the comet being an extraterrestrial spacecraft. There is no credible scientific evidence regarding an intelligent source of 3I/ATLAS. “All the evidence suggests that this is merely a vagabond comet.”succinctly puts DeBruyn. This misconception has, in part, been spread by previous coverage of the comet. “It goes without saying that a lot of media coverage has been speculation about intelligence or extraterrestrial origins and I think that’s very harmful speculation that is based on no evidence” explains Dr. Woolsey.

For Grand Rapidians who wish to try and view 3I/ATLAS, the best chance to view the comet would be to get to a dark region and to view it through a telescope, since it’s too faint to see with the naked eye. Specifically, one would be able to view the comet near the constellation Leo. However, when asked, David DeBruyn said that he knew of no successful sightings in the area, even among members of the GRAAA. Even so, he also mentioned that the winter night sky, due to the rotation of the Earth, is vastly different from the summer. This includes brighter stars than that of the summer, meaning that any hopeful 3I/ATLAS viewers won’t leave empty handed.

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Thank you for reading to the end! Special thanks to Dr. Lauren Woolsey and David DeBruyn for talking with me about the comet. This is an extended edition of a story I wrote for The Rapidian, which you can read here.

Featured Image Credit: NASA, ESA, D. Jewitt (UCLA); Image Processing: J. DePasquale (STScI)