When the news started to spread on July 1, 2025, about a new object that was spotted from outside our solar system, only the third of its kind ever known, 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, or 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.  

MSU’s Darryl Seligman, a member of the scientific team and an assistant professor in the College of Natural Science, took the lead on writing the paper.  

“I heard something about the object before I went to bed, but we didn’t have a lot of information yet,” Seligman said. “By the time I woke up around 1 a.m., my colleagues, Marco Micheli from the European Space Agency and Davide Farnocchia from NASA’s Jet Propulsion Laboratory, were emailing me that this was likely for real. I started sending messages telling everyone to turn their telescopes to look at this object and started writing the paper to document what we know to date. We have data coming in from across the globe about this object.” 

The discovery 

Larry Denneau, a member of the ATLAS team reviewed and submitted the observations from the European Southern Observatory's Very Large Telescope in Chile shortly after it was observed on the night of July 1.

Denneau said that he was cautiously excited. “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. 

“It is especially gratifying that we found it in the Milky Way in the direction of the galactic center, which is a very challenging place to survey for asteroids because of all the stars in the background,” Denneau said. “Most other surveys don't look there.” 

John Tonry, another member of ATLAS and professor at the University of Hawaii, was instrumental in design and construction of ATLAS, the survey that discovered 3I. Tonry said, “It's really gratifying every time our hard work surveying the sky discovers something new, and this comet that has been traveling for millions of years from another star system is particularly interesting.” 

Once 3I/ATLAS was confirmed, Seligman and Karen Meech, faculty chair for the Institute for Astronomy at the University of Hawaii, both managed the communications flow and worked on getting the data pulled together for submitting the paper.  

“Once 3I/ATLAS was identified as likely interstellar, we mobilized rapidly,” Meech said. “We activated observing time on major facilities like the Southern Astrophysical Research Telescope and the Gemini Observatory to capture early, high-quality data and build a foundation for detailed follow-up studies.” 

After confirmation of the interstellar object, institutions from around the world began sharing information about 3I/ATLAS with Seligman. 

What scientists know about 3I/ATLAS so far 

 
 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. “But the object is pretty far away and, so, we just don’t know.” 

Seligman and his team are specifically 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. They also want to monitor for sudden outburst events in which the object gets much brighter. 

“3I/ATLAS likely contains ices, especially below the surface, and those ices may start to activate as it nears the sun,” Seligman said. “But until we detect specific gas emissions, like H₂O, CO or CO₂, we can’t say for sure what kinds of ice or how much are there.” 

The discovery of 3I/ATLAS is just the beginning. For Tessa Frincke, who came to MSU in late June to begin her career as a doctoral student with Seligman, having the opportunity to analyze data from 3I/ATLAS to predict its future path could lead to her publishing a scientific paper of her own. 

“I’ve had to learn a lot quickly, and I was shocked at how many people were involved,” said Frincke.   

“Discoveries like this have a domino effect that inspires novel engineering and mission planning.” 

For Atsuhiro Yaginuma, a fourth-year undergraduate student on Seligman’s team, this discovery has inspired him to apply his current research to see if it is possible to launch a spacecraft from Earth to get it within hundreds of miles or kilometers to 3I/ATLAS to capture some images and learn more about the object. 

“The closest approach to Earth will be in December,” said Yaginuma. “It would require a lot of fuel and a lot of rapid mobilization from people here on Earth. But getting close to an interstellar object could be a once-in-a-lifetime opportunity.”  

“We can’t continue to do this research and experiment with new ideas from Frincke and Yaginuma without federal funding,” said Seligman, who also is a postdoctoral fellow of the National Science Foundation.  

Seligman and Aster Taylor, who is a former student of Seligman’s and now a doctoral candidate in astronomy and astrophysics and a 2023 Fannie and John Hertz Foundation Fellow, wrote the following: 

“At a critical moment, given the current congressional discussions on science funding, 3I/ATLAS also reminds us of the broader impact of astronomical research. An example like 3I is particularly important to astronomy — as a science, we are supported almost entirely by government and philanthropic funding. The fact that this science is not funded by commercial enterprise indicates that our field does not provide a financial return on investment, but instead responds to the public’s curiosity about the deep questions of the universe: Where did we come from? Are we alone? What else is out there? The curiosity of the public, as expressed by the will of the U.S. Congress and made manifest in the federal budget, is the reason that astronomy exists.” 

In addition to MSU, contributors to this research and paper include European Space Agency Near-Earth Objects Coordination Centre (Italy), NASA Jet Propulsion Laboratory/Caltech (USA), University of Hawaii (USA), Auburn University (USA), Universidad de Alicante (Spain), Universitat de Barcelona (Spain), European Southern Observatory (Germany), Villanova University (USA), Lowell Observatory (USA), University of Maryland (USA), Las Cumbres Observatory (USA), University of Belgrade (Serbia), Politecnico di Milano (Italy), University of Michigan (USA), University of Western Ontario (Canada), Georgia Institute of Technology (USA), Universidad Diego Portales, Santiago (Chile) and Boston University (USA).