Euclid, designed for the deep universe, unexpectedly discovers a comet

The European Space Agency’s Euclid space telescope has discovered a new comet, designated C/2026 S1 (Euclid), spotted at approximately 1.3 billion kilometers from Earth, between the orbits of Jupiter and Saturn. The news currently comes from a single source; independent confirmation of the observation details is not currently available.

The discovery was confirmed on October 8, 2026 by the Minor Planet Center of the International Astronomical Union, based on five images taken between September 16 and 24, 2026. The object was first identified by Mikko Pöntinen, of the University of Helsinki, together with the Euclid Consortium’s Solar System objects research group.

The comet originates from the Oort Cloud, the outermost region of the Solar System, and has an orbital period exceeding 300,000 years: an orbital cycle that means, in practice, that the object will not return to the vicinity of the Sun for a span of time far exceeding the history of observational astronomy, which began only a few centuries ago.

ESA researchers described the discovery as surprising, because Euclid is designed to study the most remote regions of the universe — dark matter and dark energy — and normally avoids the areas of sky most densely populated with asteroids and comets, precisely so as not to interfere with the cosmological observations it is intended for. “Euclid is expected to discover very few comets,” explained Bruno Altieri, an ESA researcher.

The discovery of C/2026 S1 thus comes as a byproduct, not foreseen by the telescope’s main scientific program, obtained on the margins of an observation designed for an entirely different purpose. The case confirms how instruments built for specific cosmological objectives can also produce data useful for mapping the Solar System, simply by observing portions of sky not included in their original program.