The ESA’s Euclid Telescope Discovered a New Comet Completely by Accident - CNET

A European spacecraft built to map galaxies has discovered a new comet serendipitously, proving it can do more than study dark matter and dark energy in the distant universe. The Euclid Space Telescope spotted the space snowball, dubbed C/2026 S1 (Euclid) between Sept. 16 and 24, after the renegade had smudged five image sets. The European Space Agency's mission, launched in 2023, takes long exposures of faraway galaxies, not high-speed photography of zippy objects in our own solar system. But moving-object software, developed by Mikko Pöntinen, a doctoral student at the University of Helsinki, flagged an errant streak. Finding and removing stray signals is crucial for the mission to photograph about one-third of the entire sky in every direction around Earth. "By predicting [the object's] position, I could identify it in other images," Pöntinen said in a statement. "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. "The results show Euclid, a mission in partnership with NASA, can find new comets early, while they are still fairly far from the sun.

Officially named C/2026 S1 (Euclid), the comet turned up in images Euclid captured between September 16 and 24, 2026. This Euclid shows the comet C/2026 S1 (Euclid). Image credit: ESA / Euclid / Euclid Consortium / NASA / Pöntinen et al.

The ESA's Euclid Space Telescope has discovered its first comet, a result that's not part of its primary mission. The telescope was launched at the beginning of July, 2023, and its mission is to observe about 1.5 billion galaxies out to redshift z=2, which corresponds to seeing around 10 billion years into the past. The goal is to measure the redshift of a massive amount of galaxies, to shed light on the expansion history of the Universe and the force that drives it, dark energy. The space telescope has observed other comets, but this is the first time it's discovered one. The comet was found in multiple images captured between September 16th and 24th, 2026. For a telescope built to take deep images of distant galaxies, discovering a rapidly moving comet in the Milky Way is a surprising bonus.

The European Space Agency's Euclid space telescope has discovered its first previously unknown comet in images taken between Sept. 16 and 24, 2026. The discovery is impressive for a mission that is designed to take deep, steady images of distant galaxies—not to follow fast-moving solar system objects like comets. Furthermore, the quick turnaround between identification and validation demonstrates 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.

Most people know planets are objects that go around a star, just like Earth goes around the Sun. Rogue planets are objects that have mass similar to planets but are not orbiting stars.