Euclid space telescope maps 900 million galaxies

Euclid is a space telescope built to find the universe's invisible stuff: dark matter and dark energy. On Nov. 12, ESA released Euclid's first big batch of data. It captured light from more than a billion objects. That area of sky is as big as 9,500 full moons. The dataset, called DR1-Foundation, comes from about 13 months of observations.

This isn't the discovery itself. It's the raw material future discoveries will come from. Euclid is looking for two things nobody has ever directly seen. The first is dark matter, extra gravity that seems to hold galaxies together. The second is dark energy, a force that seems to push the universe apart faster over time. Together, scientists think they make up about 95% of everything in the universe. Ordinary matter, like stars, planets, and us, is a small leftover slice. This release includes about 15,000 candidate cases of gravitational lensing. That's when a massive object bends light from something behind it, acting like a magnifying glass. Researchers will comb through those for clues about where dark matter is hiding.

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Will any of these 15,000 lensing candidates actually hold up under closer study? Most won't; these are just promising leads, not confirmed finds. Euclid still has years left in its mission. It plans to map a third of the entire sky before it's done. Each new data release should sharpen the picture a little more. The real payoff, a clearer answer on what dark matter actually is, is still years away.