NASA scientists are closely studying Interstellar Comet 3I ATLAS, a newly confirmed cosmic visitor that originated outside our solar system. The discovery marks only the third confirmed interstellar object ever observed by astronomers, making it one of the most significant space findings of 2025.
Detected by NASA’s Asteroid Terrestrial-impact Last Alert System (ATLAS) earlier this year, the comet’s trajectory and chemical composition have confirmed that it did not form in our solar system — instead, it arrived from the depths of interstellar space.
Table of Contents
Discovery of 3I ATLAS: How It Was Found
Interstellar Comet 3I ATLAS was first identified in April 2025 by the ATLAS survey, a NASA-funded automated detection network operated in Hawaii. The system, designed to spot potentially hazardous asteroids and comets, noticed a fast-moving object entering the outer solar system on an unusual hyperbolic path.
Subsequent data analysis by NASA’s Jet Propulsion Laboratory (JPL) confirmed that the comet’s orbital eccentricity — greater than 1.0 — means it is not gravitationally bound to the Sun. In other words, 3I ATLAS is just passing through our neighborhood before heading back into interstellar space.
The comet’s name, 3I, designates it as the third known interstellar object, following 1I/‘Oumuamua in 2017 and 2I/Borisov in 2019.
What Makes 3I ATLAS Unique
NASA scientists emphasize that 3I ATLAS is unlike most comets previously observed. While it shares some traits with traditional comets — such as a coma (a cloud of gas and dust) and a faint tail — its composition and speed distinguish it as a true interstellar traveler.
Some key facts about 3I ATLAS include:
| Property | Details |
|---|---|
| Discovery Date | April 2025 |
| Discovered By | NASA’s ATLAS Telescope Network |
| Designation | 3I/ATLAS |
| Estimated Speed | 68,000 mph (109,000 km/h) |
| Estimated Size | 1–2 kilometers (0.6–1.2 miles) in diameter |
| Composition | Water ice, carbon monoxide, and organic molecules |
| Trajectory | Hyperbolic — entering from interstellar space and leaving permanently |
The object’s velocity and direction indicate it likely originated from another star system located somewhere in the constellation Lyra before entering our solar system.
NASA’s Study of 3I ATLAS
NASA quickly mobilized a network of observatories and spacecraft to study Interstellar Comet 3I ATLAS before it exits the solar system. The Hubble Space Telescope, James Webb Space Telescope (JWST), and several ground-based facilities have all been gathering data on the comet’s brightness, shape, and chemical makeup.
Dr. Kelly Fast, part of NASA’s Planetary Defense Coordination Office, said researchers are particularly interested in how 3I ATLAS differs from comets formed in our solar system. The findings could provide insights into how planets and star systems form elsewhere in the galaxy.
Early spectral readings from JWST show that the comet contains a higher concentration of carbon monoxide and complex organic compounds than most local comets — evidence that it formed in a much colder, outer region of another star system.
Comparing 3I ATLAS to Previous Interstellar Visitors
3I ATLAS follows in the footsteps of two previous interstellar discoveries that changed modern astronomy:
| Name | Year Discovered | Key Features |
|---|---|---|
| 1I/‘Oumuamua | 2017 | Elongated, asteroid-like object with unusual acceleration. |
| 2I/Borisov | 2019 | Classic comet with ice and dust tail, similar to solar system comets. |
| 3I/ATLAS | 2025 | Larger, slower-brightening comet with rich carbon and organic composition. |
Unlike ‘Oumuamua, which showed no visible tail, 3I ATLAS behaves more like a traditional comet — yet its materials and orbit confirm it didn’t originate here. Its detection gives astronomers a rare opportunity to study how interstellar bodies form and evolve under completely different conditions.
Where Is 3I ATLAS Now?
As of November 2025, 3I ATLAS is moving through the inner solar system, currently passing near the orbit of Mars. The comet reached its closest approach to the Sun (perihelion) on October 12, 2025, at a distance of about 180 million miles (290 million kilometers).
The object is now moving outward, heading toward the outer solar system. It is expected to exit beyond Jupiter’s orbit by early 2026, eventually returning to interstellar space, never to return.
Although 3I ATLAS is not visible to the naked eye, astronomers and amateur skywatchers equipped with high-powered telescopes can still observe its faint greenish coma in dark-sky conditions.
What Scientists Hope to Learn From 3I ATLAS
Studying interstellar comets offers scientists a unique window into the chemistry and structure of planetary systems beyond our own. Each new object provides direct evidence of what materials exist in other star systems — materials that can’t be sampled by any spacecraft yet.
Researchers are focusing on several key objectives:
- Determine composition: Analyze ices and dust to compare them with solar system comets.
- Trace origin: Model backward trajectories to locate the comet’s source star system.
- Study organic materials: Understand whether interstellar objects contain precursors to life.
- Test planetary models: Use data to refine theories about how planets form around distant stars.
NASA’s Jet Propulsion Laboratory is also using 3I ATLAS’s movement to improve deep-space tracking algorithms, helping future missions quickly identify interstellar visitors.
Interstellar Visitors: A Growing Field of Study
Before 2017, no interstellar objects had ever been confirmed. But with improving telescope technology and sky surveys, astronomers now expect to discover several every decade.
NASA’s Vera C. Rubin Observatory, set to become fully operational in 2026, will play a major role in identifying more interstellar comets like 3I ATLAS. The observatory’s Legacy Survey of Space and Time (LSST) will scan the entire sky every few nights, catching fast-moving objects that older systems might miss.
Experts believe thousands of interstellar bodies pass through the solar system each year — most too faint or distant to detect. Each new discovery helps piece together the puzzle of how matter moves between star systems.
Will NASA Send a Mission to Study 3I ATLAS?
At the moment, NASA does not have a dedicated spacecraft capable of intercepting Interstellar Comet 3I ATLAS, due to its high velocity and short visit window. However, the agency is exploring mission concepts for future objects like it.
One proposed mission, called Comet Interceptor, a collaboration between the European Space Agency (ESA) and JAXA, aims to be on standby to chase the next interstellar visitor that enters the solar system. Launching later this decade, it could one day capture close-up data on a comet similar to 3I ATLAS.
For now, scientists are relying on remote observations from ground and space telescopes to gather as much data as possible before the comet disappears from view.
Why 3I ATLAS Matters for the Future of Space Science
Every interstellar object tells a story — one that began light-years away and may hold answers about how life and planets form across the universe.
With 3I ATLAS, NASA and the global scientific community have a chance to compare our solar system’s chemistry to that of others, deepening our understanding of cosmic origins. It’s a brief encounter, but one that could have lasting scientific value for decades to come.
As Interstellar Comet 3I ATLAS continues its journey back into deep space, astronomers remind us of a humbling truth — the universe is vast, interconnected, and full of surprises waiting to be discovered. What do you think the next interstellar visitor will reveal? Share your thoughts below and stay tuned for future updates from NASA’s cosmic frontier.