It’s official and it’s named. The object, provisionally designated A11pl3Z, showed ‘fuzziness’ (nebulosity, likely from activity) and was then given the comet designation C/2025 N1. Official discovery credit goes to the ATLAS network, Chile site (Rio Hurtado)- hence, the third designation. After the announcement of a new object, precovery images showing it on June 14 were found. Tracking the object over a sufficient arc then allowed an orbit and speed solution. C/2025 N1 is moving too fast, and thus too straight, to be in orbit around our Sun. It is, therefore, an interstellar object, coming in from somewhere outside this system, and now designated 3I/ATLAS.
https://minorplanetcenter.net/mpec/K25/K25N12.html
MPEC (Minor Planet Electronic Circular), July 2 2025
This makes ATLAS the third interstellar object we’ve detected, after 1I/‘Oumuamua in 2017 and 2I/Borisov in 2019. With three examples, we can apply some (crude) statistics and say something about groups and further populations.
https://www.nature.com/articles/d41586-025-02141-5
Rare find: interstellar visitor seen blazing through our Solar System
It has to be said: there is no threat to the Earth. No threat. The trajectories do not even cross at all. The closest 3I/ATLAS will come to Earth’s orbit, later this year, is ~0.35 AU, or just inside the orbit of Mars. That’s not even close enough to be called a NEO (Near-Earth Object).
https://www.esa.int/Space_Safety/Planetary_Defence/ESA_tracks_rare_interstellar_comet
ESA tracks rare interstellar comet
You can bet that astronomers will be training as many telescopes as they can on a visitor from another system. Unfortunately, when ATLAS is closest and warmest, it will be in solar conjunction (in daytime skies as seen from Earth) and only observable in radio bands. It will become visible to most telescopes again in December. We can, with some assumptions, say a few things already. If ATLAS has comet-like albedos (reflectivities), then it would be 10-20 kilometers in size. Big!
Obligatory Vera Rubin name-drop: the Rubin Observatory has not yet begun full sky survey operations. Once the Survey of Space and Time is truly underway, statistics suggest that interstellar objects could be detected maybe yearly, maybe more.
NewSpace or no NewSpace, there will be no mission to 3I/ATLAS. Even with the compressed schedules of modern space orgs, there’s still no way a probe could be sent by October. Even if the spacecraft were already built, and waiting on the ground, obtaining a launch and steering onto a flyby trajectory is not really likely. The Comet Interceptor mission will have a slim chance at a flyby of some presumed interstellar object, because it will already be launched, and diverted to such an object if it is spotted in time. The Comet Interceptor staff are dependent on the Rubin telescope, and its large aperture, to spot targets with more advanced notice than ATLAS or even Pan-STARRS.
And body makes three. Let’s see- literally- what four, five, etc. are like once Rubin is really running!