ESA’s Euclid telescope discovers its first previously unknown comet
ESA’s Euclid telescope detected C/2026 S1 (Euclid) in images taken between 16 and 24 September 2026, despite being designed to map distant galaxies rather than track comets. The International Astronomical Union’s Minor Planet Center confirmed it on 8 October after software developed by University of Helsinki researcher Mikko Pöntinen flagged the object for follow-up.
Bottom line — C/2026 S1 is about 1.3 billion kilometres from Earth and is not a target for ESA’s Comet Interceptor.
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ESA says Pöntinen’s software found the comet in five image sets; follow-up inspection revealed a diffuse cloud of dust and gas.
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According to ESA, Euclid avoids the Solar System’s comet-rich plane to limit dust glare and usually observes each patch of sky only once.
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The comet appeared in 16 exposures across five fields of view in Euclid’s Deep Field North, ESA reports.
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ESA says the discovery and alert process gave the Euclid and Comet Interceptor teams a test case for future coordination.
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The Minor Planet Center’s orbit will be refined as more observations are collected, ESA says.