Euclid discovers its first new comet 810 million miles from Earth

The European Space Agency's Euclid space telescope has identified its first previously unknown comet located roughly 1.3 billion kilometers (810 million miles) from Earth. This discovery occurred between September 16 and 24, 2026, during routine deep imaging of distant galaxies, which is outside Euclid's primary mission of mapping galaxies.

Mikko Pöntinen, a researcher from the University of Helsinki and a member of the Euclid Consortium's Solar System Objects Science Working Group, developed software to detect fast-moving solar system objects like comets in Euclid's images. Pöntinen noticed a streak in the images, which turned out to be a fuzzy cloud indicative of a comet shedding dust and gas.

After ruling out matches with known comets and asteroids, the International Astronomical Union's Minor Planet Center confirmed the discovery as comet C/2026 S1 (Euclid) on October 8.

The comet is currently located above the solar system plane, far from the orbits of planets, making it a challenging target for future missions like the Comet Interceptor. Euclid deliberately avoids the asteroid-rich plane of the solar system to reduce glare from dust and improve deep-sky imaging quality. While this discovery is limited in number, it showcases Euclid's capability to detect distant comets, which will aid future coordination between the Euclid and Comet Interceptor missions.