Third Interstellar Comet 3I/ATLAS Enters Solar System

Comet 3I/ATLAS—the third interstellar visitor ever recorded—was spotted by ATLAS in Chile, speeding toward perihelion at 37 mi/s.

Discovery of a Cosmic Interloper

Astronomers have identified a new interstellar comet designated 3I/ATLAS. It represents only the third interstellar object ever recorded passing through our solar system. Detection came on July 1, when an ATLAS telescope in Rio Hurtado, Chile, flagged a faint moving speck. Observations revealed a hyperbolic trajectory, confirming an origin far beyond the Sun’s gravitational reach. NASA confirmed that 3I/ATLAS hurtles toward our planetary neighborhood at roughly 37 miles per second.

University of Hawaii astronomer Larry Denneau, co-principal investigator for ATLAS, noted that knowledge of its composition remains limited. He added that teams are lining up larger optical and radio telescopes to probe its make-up.

Characteristics and Orbital Path

Initial size estimates suggest a nucleus up to 10 kilometers in diameter, dwarfing comet 2I/Borisov. Cometary activity is already faintly visible, forming a small coma around the icy core. Tail development could accelerate dramatically during the comet’s inward swing. Perihelion is set for late October, when 3I/ATLAS will skim inside Mars’s orbit yet remain more than 150 million miles from Earth.

High-speed motion of around 60 km/s traces back to the Milky Way’s heart, implying an origin near the galactic center. Trajectory analysis indicates no risk to Earth, with a minimum solar distance planned at 1.4 astronomical units.

Global Observation Efforts

Worldwide astronomers are mobilizing to study this rare visitor. Multiple observatories and space telescopes aim to gather data on its composition, shape, and reflectivity. ATLAS, a network managed by the University of Hawaii, scanned the sky continuously across five sites, leading to the timely discovery. Telescopes like the Vera C. Rubin Observatory and instruments at Palomar are preparing follow-up observations this summer.

Future observations could reveal insights into the formation conditions of exoplanetary systems. Past interstellar findings—’Oumuamua in 2017 and Borisov in 2019—paved the way by showcasing the diversity of objects drifting between stars. Improved survey instruments now increase the odds of catching other visitors, transforming our understanding of cosmic material exchange. Archived observations from Caltech’s Zwicky Transient Facility extended the comet’s known path back to June 14.