NASA Identifies 3I/ATLAS as 3rd Interstellar Object at 210,000 Kilometers per Hour
Updated
Updated · spacedaily.com · Jun 29
NASA Identifies 3I/ATLAS as 3rd Interstellar Object at 210,000 Kilometers per Hour
3 articles · Updated · spacedaily.com · Jun 29
Summary
3I/ATLAS was confirmed after ATLAS spotted a faint moving object from Chile on July 1, 2025 and follow-up measurements showed a hyperbolic, unbound path through the solar system.
210,000 kilometers per hour helped mark it as an interstellar visitor rather than a normal comet, while pre-discovery images from June 14 strengthened the orbit calculation.
NASA said the object posed no threat to Earth, passing no closer than about 1.8 astronomical units, with its closest solar approach around 1.4 AU on Oct. 30, 2025.
Hubble later saw a dust cocoon and plume consistent with comet activity, with the hidden nucleus estimated at no more than 5.6 kilometers across and possibly as small as 440 meters.
The find makes 3I/ATLAS only the third confirmed interstellar object after ʻOumuamua in 2017 and Borisov in 2019, giving astronomers a rare new sample from another planetary system.
Are countless objects like 3I/ATLAS the galaxy's 'missing mass' we attribute to dark matter?
Could this ancient interstellar visitor be a remnant from one of the galaxy's first planetary systems?
Its water is unlike anything in our solar system. What does this reveal about planets forming elsewhere?
3I/ATLAS: The Third Interstellar Visitor Reveals Exotic Chemistry and Challenges Our Understanding of the Galaxy
Overview
In the latter half of 2025, astronomers announced the arrival of 3I/ATLAS, the third interstellar object ever detected in our Solar System. Its '3I' designation highlights its place after 'Oumuamua and 2I/Borisov. These rare interstellar visitors, including 3I/ATLAS, offer unique opportunities to study materials from beyond our solar system. By observing 3I/ATLAS, scientists gain direct insights into the diversity and dynamics of stellar populations across the Milky Way, helping us better understand the origins and evolution of planetary systems far from our own.