The European Space Agency's Euclid space telescope has discovered its first previously unknown comet, spotted sailing through space more than 807 million miles from Earth, Popular Science reported. The find is remarkable because Euclid, launched in July 2023 on a six-year mission to study dark matter and dark energy, was designed to stare at distant galaxies, not to chase fast-moving objects in our own solar system.
The discovery was made by Mikko Pöntinen, a PhD student at the University of Helsinki, whose moving-object detection software flagged a streak smeared across several images. “I was excited to see my software flag a streak smeared across several images, the result of a fast-moving object,” Pöntinen said, according to ESA. “Further inspection revealed that it had a fuzzy cloud around it, indicative of an active object like a comet that is shedding dust and gas.”
By predicting the object's position, Pöntinen identified it in five image sets, 16 exposures in total, taken between September 16 and 24, 2026. Checks against catalogs of known comets and asteroids found no match, so he reported the observations to the International Astronomical Union's Minor Planet Center, which confirmed it as a comet on October 8. It is now designated C/2026 S1 (Euclid).
The comet sits about 1.3 billion kilometres from Earth, roughly between the orbits of Jupiter and Saturn, but far above the plane of the planets on an orbit that will take thousands of years to complete, ESA said. The quick turnaround between identification and validation proves Euclid can detect new comets while they are still far from the Sun, offering a real test case for coordination with ESA's future Comet Interceptor mission, planned for launch in late 2028 or early 2029.