The European Space Agency’s Euclid space telescope discovered its first previously unknown comet, now designated C/2026 S1 (Euclid), in images taken between September 16 and 24, 2026.
University of Helsinki PhD student Mikko Pöntinen spotted it with moving-object detection software he wrote for Euclid’s images, working with the Euclid Consortium’s Solar System Objects Science Working Group. The comet showed up as a streak in 16 exposures across five fields of view in the Euclid Deep Field North, and a fuzzy cloud around it showed it was shedding dust and gas. Because it matched nothing in catalogs of known comets and asteroids, the team reported it to the International Astronomical Union’s Minor Planet Center, which confirmed it as a comet on October 8. It lies about 1.3 billion kilometers (810 million miles) from Earth, high above the plane of the planets, on an orbit that will take thousands of years to complete. The find is unusual because Euclid is built to map distant galaxies and deliberately avoids the comet-rich band of sky along the solar system’s plane.
Image: ESA/Euclid/Euclid Consortium/NASA, M. Pöntinen et al. 2026, CC BY-SA 3.0 IGO.
Source: European Space Agency — Euclid discovers new comet
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