3I/ATLAS: Scientific Paper Details What's Known About the Third-Ever Interstellar Object
When the news started to spread on July 1, 2025, about a new object that was spotted from outside our solar system, astronomers at Michigan State University—along with a team of international researchers—turned their telescopes to capture data on the new celestial sighting.
The team rushed to write a scientific paper on what they know so far about the object, now called 3I/ATLAS, after NASA's Asteroid Terrestrial-impact Last Alert System (ATLAS). ATLAS consists of four telescopes—two in Hawaii, one in Chile, and one in South Africa—which automatically scans the whole sky several times every night looking for moving objects.
The research is published on the arXiv preprint server.
The Discovery
Larry Denneau, a member of the ATLAS team, reviewed and submitted the discovery observations from the European Southern Observatory's Very Large Telescope in Chile shortly after it was observed on the night of July 1.
Denneau stated, "We have had false alarms in the past about interesting objects, so we know not to get too excited on the first day. But the incoming observations were all consistent, and late that night it looked like we had the real thing."
Details About 3I/ATLAS
- It is only the third interstellar (meaning from outside our solar system) object to be detected passing through our solar system.
- It's potentially giving off gas like other comets do, but that needs to be confirmed.
- It's moving really fast at 60 kilometers per second, or 134,000 miles per hour, relative to the sun.
- It's on an orbital path that is shaped like a boomerang or hyperbola.
- It's very bright.
- It's on a path that will leave our solar system and not return, but scientists will be able to study it for several months before it leaves.
Scientific Implications
The James Webb Space Telescope and the Hubble Space Telescope are expected to reveal more information about its size, composition, spin, and how it reacts to being heated over the next few months. "We have these images of 3I/ATLAS where it's not entirely clear and it looks fuzzier than the other stars in the same image," said James Wray, a professor at Georgia Tech.
Seligman and his team are particularly interested in 3I/ATLAS's brightness because it informs us about the evolution of the coma, a cloud of dust and gas. They've been tracking it to see if it has been changing over time as the object moves and turns in space.
“3I/ATLAS likely contains ices, especially below the surface, and those ices may start to activate as it nears the sun,” Seligman highlighted. “But until we detect specific gas emissions, like H₂O, CO, or CO₂, we cannot say for sure what kinds of ice or how much are there.”
Future Research and Collaboration
The discovery of 3I/ATLAS is just the beginning. Researchers from various institutions are pooling their knowledge and resources to enhance studies surrounding this remarkable object. They endeavor to uncover more about its procession and manifestations while contributing significantly to our understanding of interstellar objects.
Conclusion
3I/ATLAS not only poses questions about its physical properties but also elicits broader curiosity regarding the capabilities and future objectives of astronomical research in both governmental and educational contexts. The scientific community is eagerly anticipating new findings as the telescopes gather data.
In the words of Seligman, "The fact that this science is not funded by commercial enterprise illustrates that our field does not provide a financial return on investment but responds to the public's curiosity about the universe's deep questions: Where did we come from? Are we alone? What else is out there?"
References
More information: Darryl Z. Seligman et al., Discovery and Preliminary Characterization of a Third Interstellar Object: 3I/ATLAS, arXiv (2025). DOI: 10.48550/arxiv.2507.02757
For a more comprehensive reading of the scientific process, methodology, and future objectives regarding 3I/ATLAS, refer to the article on arXiv.
