WORLDTECHEuclid Telescope Finds Its First Comet, Named C/2026 S1 (Euclid)
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The European Space Agency's Euclid space telescope has discovered a comet, its first, a finding that falls outside its primary mission of mapping galaxies. The object has been designated C/2026 S1 (Euclid), according to a report by Universe Today.
How the comet was identified
The comet was spotted in several images the telescope captured between September 16 and 24, 2026. Mikko Pöntinen of the University of Helsinki, working with the Solar System Objects Science Working Group of the Euclid Consortium, identified it using new software he designed.
Pöntinen compared the object with known comets and asteroids and found no match among existing Solar System bodies. He reported the discovery to the Minor Planet Center, which handles identification, designation and orbit computation for Solar System objects. Ground-based follow-up observations helped confirm the find, and the center assigned the name C/2026 S1 (Euclid), following its usual convention.
Surprise outcome of a galaxy survey
Euclid was launched in July 2023 to observe about 1.5 billion galaxies out to a redshift of z=2, a survey meant to reveal how the universe has expanded over roughly 10 billion years and to shed light on dark matter and dark energy. Finding a fast-moving comet within the Milky Way is, by the account of Universe Today, an unexpected bonus for a telescope built to image distant galaxies.
The telescope has observed comets before, but this is the first one it has discovered. Universe Today notes that Euclid deliberately avoids the part of the sky aligned with the plane of the Milky Way, where dust makes deep imaging difficult, while most asteroids and comets follow that plane.
Why comets matter to astronomers
Comets are dusty, icy remnants from the early Solar System, more than four billion years old. As they approach the Sun, the heat releases frozen material that forms a hazy coma and a tail. Astronomers value them as untouched material from the Solar System's formation and as possible carriers of water to the inner Solar System, including Earth.
C/2026 S1 (Euclid) lies about 1.3 billion km from Earth, roughly the distance from the Sun to a point halfway between the orbits of Jupiter and Saturn. It is a long-period comet that needs thousands of years to complete one orbit.
Open questions
- How will follow-up observations refine the comet's orbit?
- Will further Euclid data reveal more objects outside its galaxy survey?