Overview
- Images taken by Euclid between September 16 and September 24, 2026 captured a streak seen across 16 exposures in five fields that led to the discovery.
- PhD student Mikko Pöntinen of the University of Helsinki identified the object using dedicated moving‑object software and reported it to the Euclid team.
- The International Astronomical Union’s Minor Planet Center confirmed the object as a new comet, designated C/2026 S1 (Euclid), on October 8 after coordinating ground‑based follow‑up.
- C/2026 S1 (Euclid) lies about 1.3 billion kilometres from Earth on a high‑inclination orbit that will take thousands of years to complete and shows a fuzzy coma consistent with an active comet.
- The comet is not a candidate for ESA’s Comet Interceptor, but the discovery is a practical test of Euclid’s moving‑object processing and the alert workflow that removes moving contaminants from deep‑sky surveys and enables further study of primitive Solar System bodies.