A day’s worth of data from Euclid has produced a huge view of the Milky Way’s centre, and scientists say it could help find many more planets beyond our solar system.
In 2025, the European Space Agency spacecraft turned to the heart of the Milky Way for 26 hours and created what the source describes as the largest and most detailed photo of this region of the galaxy ever made. The image contains 60 million stars and 51 known planetary systems.
Euclid is built to study dark energy by observing distant galaxies. That also makes it powerful enough to pick out individual stars in the Milky Way’s central bulge, a region where other telescopes are too affected by the dense concentration of stars to do the same.
Astronomers asked Euclid to monitor the galactic bulge because it is a strong region for microlensing events. These happen when an object with mass warps space and bends light from a background source. In planet searches, a star passes in front of another star and acts as a gravitational lens, and a planet creates a small disturbance in that light pattern.
“To catch microlensing, you need to observe parts of the sky that are crowded with stars, such as close to the center of our galaxy,” team leader Jean-Philippe Beaulieu of the Institut d’Astrophysique de Paris in France said in a statement.
“During the last twenty years, almost 300 exoplanets have been discovered using this technique, all with ground-based telescopes and all towards the center of our galaxy,” Beaulieu said. “This image from Euclid includes 51 known planetary systems – and it will assist in studying many more that will be found.”
The Euclid data does not contain microlensing events because detecting them takes about 20 days. Instead, the image is expected to act as a reference for longer observations by future missions, including NASA’s Nancy Grace Roman Space Telescope.
“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,” team member Natalia Rektsini of the Institut d’Astrophysique de Paris said.
“This means that anyone who detects a microlensing event in the same region, for example, with Roman, will be able from now on to use Euclid data as a time reference in the past and see how the stars looked before they overlapped. Since Euclid can clearly separate individual stars, one can then measure how fast they move over time and use that information to confirm the existence of a planet and determine its mass. This would not be possible with data from one point in time.”
The source says microlensing can detect smaller planets farther from their host stars than some other planet-hunting methods, including ice giants such as Uranus and Neptune in wide orbits around stars in the galactic bulge.
“This result shows what a relatively small, dedicated team can achieve within a large international mission,” said Valeria Pettorino, Euclid Project Scientist at ESA. “That’s why this Euclid data will be a time reference for past and future missions and enable studies of exoplanets and their masses. This data can also be used for other scientific applications, from brown dwarfs and binary stars to stellar motions and dust across our galaxy.”
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