An interstellar visitor just entered our Solar System
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In July 2025, astronomers identified an exceptionally rare interstellar comet currently speeding through our Solar System. The object has been designated 3I/ATLAS and is only the third confirmed interstellar visitor ever discovered: the first was ‘Oumuamua in 2017, and the second was 2I/Borisov in 2019.
Discovery and observations
3I/ATLAS was detected on 1 July 2025 by the NASA-funded ATLAS (Asteroid Terrestrial-impact Last Alert System) telescope located in Chile. Initially labelled C/2025 N1 (ATLAS), the Minor Planet Center (MPC) soon reclassified it as 3I/ATLAS, signalling its status as the third known interstellar object, writes EarthSky.
Following its discovery, astronomers reviewed archival images dating back to 14 June 2025, confirming the comet’s presence. Current observations place the object approximately 4.5 astronomical units (about 670 million kilometres) from the Sun, with an apparent magnitude of roughly 18.8—too faint for amateur telescopes to observe.
Orbit and closest approaches
3I/ATLAS follows a highly hyperbolic trajectory, unequivocally indicating an interstellar origin. It is travelling at a speed of 68 km/s (152,000 km/h) relative to the Sun and poses no threat to Earth.
The comet will reach perihelion (closest approach to the Sun) on 30 October 2025, at a distance of 1.4 astronomical units (210 million kilometres), inside the orbit of Mars. Its closest approach to Earth will occur on 19 December, at about 1.8 astronomical units (270 million kilometres) away, reports Space.com.