Third Interstellar Comet 3I/ATLAS Detected by ATLAS Survey in Chile

On 1 July 2025 the ATLAS (Asteroid Terrestrial-Impact Last Alert System) telescope at Rio Hurtado, Chile reported a faint moving point to the Minor Planet Center. Follow-up astrometry revealed an open, hyperbolic trajectory that cannot be bound to the Sun. NASA classified the object as 3I/ATLAS, the third confirmed interstellar visitor after ‘Oumuamua (2017) and Borisov (2019). The comet will exit the solar system after a brief passage.

In July 2025, the ATLAS sky survey in Chile spotted a faint comet racing through the solar system at roughly 130,000 miles per hour — and follow-up orbit calculations quickly showed it was not bound t

Pre-discovery images from other ATLAS sites and Caltech’s Zwicky Transient Facility extended back to 14 June 2025. The comet reached perihelion on 30 October 2025 at ?1.4 AU from the Sun, just inside Mars’ orbit, and passed Earth at 1.8 AU (?170 million mi). In the ensuing months, Hubble, Webb, TESS, Swift, SPHEREx and several planetary-mission instruments collected spectroscopic and imaging data.

In July 2025, the ATLAS sky survey in Chile spotted a faint comet racing through the solar system at roughly 130,000 miles per hour — and follow-up orbit calculations quickly showed it was not bound t

ESA/Hubble measured a heliocentric speed of ?210 000 km h?¹ (?130 000 mph), the fastest recorded for any solar-system entrant. The comet showed a typical coma and tail, confirming volatile-rich composition. Its hyperbolic excess velocity and lack of a closed orbit confirmed its interstellar nature. The faint magnitude required repeated observations to refine the orbit and verify cometary activity.

In July 2025, the ATLAS sky survey in Chile spotted a faint comet racing through the solar system at roughly 130,000 miles per hour — and follow-up orbit calculations quickly showed it was not bound t

With three confirmed interstellar objects, astronomers can move beyond a single-case paradigm. 3I/ATLAS shows that modern surveys can detect fast, faint interstellar comets missed a decade ago. The multi-instrument campaign demonstrates that coordinated space-based and ground-based observations are essential to determine composition, outgassing and origin. The event also underscores ATLAS’s dual role in planetary-defence and interstellar science.

In July 2025, the ATLAS sky survey in Chile spotted a faint comet racing through the solar system at roughly 130,000 miles per hour — and follow-up orbit calculations quickly showed it was not bound t

NASA described 3I/ATLAS’s trajectory as open, confirming an origin outside the solar system and that it will not be captured by solar gravity. NASA also emphasized the comet’s path kept it far from Earth, posing no impact risk. ESA/Hubble highlighted the record-breaking velocity as key to recognizing its interstellar nature. Both agencies said the event validates the scientific return of planetary-defence surveys.

In July 2025, the ATLAS sky survey in Chile spotted a faint comet racing through the solar system at roughly 130,000 miles per hour — and follow-up orbit calculations quickly showed it was not bound t

• “ESA/Hubble later described 3I/ATLAS as travelling at roughly 210,000 kilometres per hour, or about 130,000 miles per hour, the highest velocity recorded for a solar-system visitor.” — ESA/Hubble

In July 2025, the ATLAS sky survey in Chile spotted a faint comet racing through the solar system at roughly 130,000 miles per hour — and follow-up orbit calculations quickly showed it was not bound t

• “The speed of 3I/ATLAS made it compelling, but it also made careful framing necessary.” — NASA overview

In July 2025, the ATLAS sky survey in Chile spotted a faint comet racing through the solar system at roughly 130,000 miles per hour — and follow-up orbit calculations quickly showed it was not bound t

• “It was debris from elsewhere, following physics.” — SpaceDaily, concluding remarks

In July 2025, the ATLAS sky survey in Chile spotted a faint comet racing through the solar system at roughly 130,000 miles per hour — and follow-up orbit calculations quickly showed it was not bound t

Continued monitoring by Hubble, Webb and ground-based telescopes will refine compositional models of 3I/ATLAS. NASA plans to add interstellar-object detection to future ATLAS upgrades and to surveys such as the Vera C. Rubin Observatory. The event underscores the need for rapid-response networks to capture fleeting interstellar visitors for scientific study.

In July 2025, the ATLAS sky survey in Chile spotted a faint comet racing through the solar system at roughly 130,000 miles per hour — and follow-up orbit calculations quickly showed it was not bound t