Video
Comet C/2026 S1 (Euclid) streaks across the sky (annotated)
The European Space Agency's Euclid space telescope has discovered its first previously unknown comet: C/2026 S1 (Euclid).
In this image sequence it moves against background stars and galaxies in three of Euclid’s VIS camera exposures captured during the Euclid Deep Field North survey.
The images were taken at 00:41:07, 00:58:53 and 01:16:39 UTC on 17 September 2026. Each image is a 560.52 second exposure, so the comet appears like a streak because it moves across the sky during the long exposure. A fuzzy atmosphere, known as a ‘coma’ in cometary terms, is seen around the object.
CREDIT ESA/Euclid/Euclid Consortium/NASA, M. Pöntinen et al. 2026
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The European Space Agency’s Euclid space telescope has discovered its first previously unknown comet, in images taken between 16 and 24 September 2026.
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The discovery is impressive for a mission that is designed to take deep, steady images of distant galaxies – not for following fast-moving Solar System objects like comets [2]. Furthermore, the quick turnaround between identifying and validation proves the case that Euclid can detect new comets while they are still relatively far from the Sun, potentially leading to a suitable target for ESA’s future Comet Interceptor mission.
Mikko Pöntinen of the University of Helsinki, together with the Solar System Objects Science Working Group of the Euclid Consortium, made the initial discovery using moving object detection software that Mikko developed to monitor small Solar System objects in Euclid’s images: “I was excited to see my software flag a ‘streak’ smeared across several images – the result of a fast-moving object. By predicting its position I could identify it in other images, in total finding it in five image sets. 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.”
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https://www.esa.int/Science_Exploration/Space_Science/Euclid/Euclid_discovers_new_comet?fbclid=IwY2xjawVEQbtleHRuA2FlbQIxMABwZG9mAXNydGMGYXBwX2lkEDIyMjAzOTE3ODgyMDA4OTIAAR7PFi_Y-jXqc2cd30qJsqvxwB0lsCEZ24FOjMAI6LHPSPguqhIufoCZSF_Yyw_aem_r991ETL2kiI39X624jY-Jg