Euclid’s Record-Breaking Portrait of the Milky Way’s Core Opens New Path for Exoplanet Microlensing

On 23–24 March 2025 Euclid captured the largest visible-light mosaic of the Milky Way’s bulge, stitching nine pointings that cover an area equivalent to ~22 full moons and contain >60 million stars, recorded in 26 hours.

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Euclid, launched in 2023, surveys dark matter and dark energy across one-third of the sky. Its visible-light camera matches Hubble’s sharpness while covering a field 270 times larger per pointing. The bulge observation was led by Jean-Charles Cuillandre (Euclid mission), Jean-Philippe Beaulieu (Institut d’Astrophysique de Paris & University of Tasmania), Natalia Rektsini (survey leader) and Eamonn Kerins (University of Manchester).

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Microlensing uses a foreground star’s gravity to brighten a background star; a planet adds a subtle signal. Euclid’s pre-event snapshot lets the Roman Space Telescope compare future microlensing events to known stellar positions, confirming planets and measuring masses. The data also support studies of brown dwarfs, binaries and interstellar dust.

ZME ScienceScienceAlertEarth & SkyEuclid Captures Most Detailed Visible-Light Image Ever Taken of Milky Way’s Core

ESA said the image will aid the search for planets beyond the Solar System and highlighted its microlensing value. Euclid scientists noted the camera resolves individual stars in the crowded bulge without saturation. NASA JPL emphasized the extensive planning required, and LSU researchers called the dataset a rare chance to test Mil Way models.

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The image did not discover new exoplanets; microlensing events need longer monitoring than the 26-hour exposure. Color was added from Canada-France-Hawaii Telescope data. Future Roman observations are needed to detect and confirm planets.

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• “Now we've decided to point Euclid at the brightest area of the sky – and it works superbly, it's extraordinary,” — Jean-Charles Cuillandre, French astronomer, Euclid mission

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• “During the last 20 years, almost 300 exoplanets have been discovered using this technique, all with ground-based telescopes and all towards the centre of our galaxy,” — Jean-Philippe Beaulieu, Institut d’Astrophysique de Paris & University of Tasmania

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• “The leader of the Euclid galactic bulge survey, Natalia Rektsini, said: In 24 hours, Euclid has already captured the stars involved in all the future microlensing events that the Roman space telescope will detect, but before the stars and planets involved have aligned.” — Natalia Rektsini, leader of Euclid galactic bulge survey

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• “This data fires the starting pistol in a new age of exoplanet discovery, where we go from knowing about 6,000 exoplanets to finding more than 100,000 across the galaxy,” — Dr. Eamonn Kerins, University of Manchester

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Euclid’s snapshot will serve as a reference for the Roman Space Telescope’s microlensing survey, enabling precise planet-mass measurements and supporting studies of isolated black holes, rogue planets and Mil Way structure.

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