A Helsinki student's software spots a brand-new comet 810 million miles away

The Euclid space telescope was built to map distant galaxies — nobody expected it to find comets. But software written by Mikko Pöntinen of the University of Helsinki flagged a faint streak in Euclid images taken in September, and follow-up checks confirmed it: a previously unknown comet, now named C/2026 S1 (Euclid), sitting about 1.3 billion kilometres (810 million miles) from Earth. It is Euclid's first comet discovery, made not by the telescope's designers' plan but by a researcher watching for exactly the kind of surprise the mission never promised.