Imagine something older than the Sun, quietly gliding through our solar system right now. On July 1, 2025, astronomers using the ATLAS survey telescope in Chile spotted something extraordinary: a comet-like object named 3I/ATLAS (C/2025 N1). But this isn’t your average space rock—it’s the 3I/ATLAS Interstellar Comet, a rare visitor not born in our solar system. Even more astonishing, scientists believe it could be over 7 billion years old, making it one of the oldest objects humanity has ever observed.
Yes—you read that right. This rock could be nearly twice as old as our entire solar system.
Just How Old Is 3I/ATLAS?
So, how do we know it’s that ancient?
Dr. Matthew Hopkins from the University of Oxford led a preliminary age analysis. His models suggest that 3I/ATLAS could date back over 7 billion years, making it the oldest known comet ever observed. For context, our solar system is “only” about 4.5 billion years old.
What backs this up? Its unusual speed and trajectory. This object seems to have originated from the Milky Way’s thick disk—a region filled with older stars and low-metal content, both signs of ancient formation.
Some conservative estimates place its age around 5 billion years, but the cosmic clues are leaning older.
What Makes It Different?
Aside from its age, 3I/ATLAS behaves quite differently than typical comets.
Its orbital path is extreme, with:
- Eccentricity: ~6.1 (a truly wild trajectory)
- Perihelion: ~1.36 AU (that’s roughly where Earth orbits)
- Inclination: ~175° (almost a complete flip in direction)
- Hyperbolic speed: ~58 km/s (lightning fast in space terms)
And while it shows some cometary activity, it’s far less dramatic than 2I/Borisov—the last interstellar comet we encountered in 2019.
Where Did It Come From?
Current research points to the thick disk of the Milky Way as the object’s birthplace. This part of our galaxy is home to some of the oldest stars—likely where 3I/ATLAS formed billions of years ago, before drifting into the vast emptiness of interstellar space.
Its chemical fingerprints, velocity, and trajectory all align with this ancient origin story.
Why This Matters for Science
You might be wondering: why is this such a big deal?
Well, 3I/ATLAS is only the third interstellar object ever observed in our solar system. The first was 1I/’Oumuamua in 2017, and the second was 2I/Borisov in 2019.
What makes this one so exciting is its incredible age. Studying it could give scientists rare access to the raw building blocks that existed before our Sun even formed. Early data hints at water-rich materials, which could help explain how volatiles—like water and organic compounds—traveled across the galaxy.
What’s Next for 3I/ATLAS?
As the object approaches its closest point to the Sun (perihelion), telescopes around the world will keep a close eye on it.
Researchers hope to:
- Confirm its age through spectroscopic analysis
- Identify chemical signatures that reveal its makeup
- Understand how interstellar objects like this shape the story of planetary formation
This is a once-in-a-generation opportunity to learn about matter that predates our very existence.
Sources & Further Reading
- Hopkins, M. (2025). Preliminary Age Analysis of Interstellar Object 3I/ATLAS. Royal Astronomical Society, NAM 2025.
- ATLAS Survey Team. (2025). Discovery and Characterization of 3I/ATLAS. Minor Planet Center Circular.
- Smith, J. et al. (2025). Discovery of Third Interstellar Object. arXiv:2507.02757.
- NASA Planetary Defense Coordination Office. (2025). NASA Reports on 3I/ATLAS.
- Williams, R. et al. (2025). Galactic Origin of 3I/ATLAS. arXiv (submitted).
- International Astronomical Union. (2025). Official Designation Notice. IAU Circular.
