That discovery, he said, changed his life. 

Since then, Michigan State University Assistant Professor Darryl Seligman has led the first ever scientific paper published about 3I/ATLAS — a project he co-authored with Yaginuma, graduate student Tessa Frincke and several other collaborators. 

Both Yaginuma and Frincke have since submitted their own scientific papers on the subject, which are now pending approval.

For Yaginuma, the discovery came at exactly the right moment. From then on, his summer research shifted entirely to 3I/ATLAS, taking his work in a new direction.

The first paper on 3I/ATLAS was assembled quickly, with more than 40 collaborators contributing. Yaginuma said being part of the team felt like a turning point.

“For me as an undergrad, the first discovery paper is basically one that gets a lot of citations,” he said. “Even though there were about 40 people on it, being part of that community means I can keep working with them in the future”

Frincke had a similar experience to Yaginuma. She had just arrived at MSU for her first year in the astrophysics program and planned to ease into research. Instead, she was thrust into a race to capture and interpret the first data on a once-in-a-lifetime object.

“I started doing normal research and then all of the sudden (Seligman) is emailing me at midnight saying that it could be an interstellar object,” she said. “It kind of blew up from there.” 

Frincke soon found herself leading observations using the Southern Astrophysical Research telescope in Chile remotely, from East Lansing.

Frincke did the observing work and data reduction, analyzing the object’s brightness and light curve over time. While Seligman provided guidance on writing, she had to jump into the deep end and figure out much of the process on her own.

“It's pretty exciting, and it's definitely put me on the map as far as my career and all of that,” she said. “Like being able to publish my first author paper. It's still in review, but still, it's huge for me.”

Part of what makes 3I/ATLAS so intriguing, she explained, is how different it is from the first two interstellar objects. 

“It’s way faster — 58 kilometers per second compared to 26 or 32 for the first two. That tells us it’s much older,” Frincke said. “And it has a tail showing sublimation of water ice and CO₂, unlike the first one.”

For Seligman, the discovery was both exhilarating and urgent. He recalled the night the ATLAS survey first flagged the object. 

When the ATLAS survey first flagged the object, Seligman immediately began working with colleagues at NASA and in Europe to confirm its trajectory.

“Within hours we realized this thing was hyperbolic — it was for sure interstellar — and everyone started freaking out,” he said. 

At first, he thought it was simply enormous and unusually bright. Later, his team realized the brightness came from cometary activity — ice sublimating and spitting out dust. 

“That made it stand out as totally different from the first two interstellar objects,” he said

Because 3I/ATLAS is on a one-time path through the solar system, the window to study it is short. The comet will reach perihelion in late October, passing behind the Sun from Earth’s perspective and blocking ground-based observations at the very moment its activity peaks.

“This thing comes through and never comes back,” Seligman said. “You want as many observations as possible. At perihelion it’ll be most active, but we can’t see it from Earth then, so that's very frustrating, but that doesn't mean that we'll be totally set back.”

Instead, scientists are looking beyond Earth. NASA is working to enlist its existing fleet of space-based assets — including spacecraft orbiting Mars — to help monitor 3I/ATLAS when ground-based telescopes fall dark. One of Yaginuma’s papers even explores how a Mars orbiter could be repurposed to capture valuable data during the comet’s hidden approach.