This comet (also designated 3I/ATLAS) was discovered on 1 July 2025 by the ATLAS survey system. It is remarkable for its eccentricity, greater than six. What that means is that it's traveling much faster than the Sun's escape velocity, and is therefore not part of our solar system. It is a comet that was born around another star and was ejected from that system, traveling for millions of years before its chance encounter with our star. Large telescopes reveal a distinct tail, which is why it is categorized as a comet and not an asteroid. This is only the third interstellar object to be detected passing through the Solar System.

Detected near the orbit of Jupiter, it will pass between Earth and Mars in October, becoming brighter and easier to image. The tail may become more visible as it enters the warmer inner system, as well. It is in a retrograde orbit nearly lying on the plane of the Solar System (the ecliptic).

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