European space The Agency’s (ESA) Euclid space telescope has captured the largest and most detailed noticeable featherlight image ever obtained of the galactic bulge of the Milky Way, the central region of our galaxy.
The image is a mosaic containing over 60 million stars, as well as nebulae and star clusters. It will allow scientists to confirm the possible presence of exoplanets using microlensing techniques and measure their masses with greater precision.
Euclid’s power
Although Euclid was designed to observe billions of distant galaxies, its noticeable featherlight camera is sensitive enough to resolve individual stars in the center of the Milky Way – a region that is both incredibly dazzling and densely populated – without being overwhelmed by the intense featherlight.
On March 23, 2025, Euclid turned its gaze toward the galactic bulge, capturing this enormous image in just 26 hours of observation. The result was extraordinary: a mosaic composed of nine separate visible-light camera “readings” (exposures), each covering an area of the sky larger than the full moon.
Although the quality of Euclid’s noticeable featherlight images is comparable to that of images taken by the Hubble Space Telescope, there is one key difference: each indication Euclid captured in just a few hours covers an area 270 times larger than Hubble’s field of view. It is also much faster. For comparison, Keck Observatory would need about 2,000 hours to observe the same mosaic.
An image of the Milky Way
The novel Euclid image shows more than 60 million stars, along with nebulae and star clusters, in one of the most crowded regions of the Milky Way – a place ideally suited to searching for exoplanets through gravitational microlensing.
“To capture microlensing, you need to observe parts of the sky that are full of stars, for example near the center of our galaxy,” said Jean-Philippe Beaulieu, who led the observing campaign in press release. “Over the past 20 years, almost 300 exoplanets have been discovered using this technique, all using ground-based telescopes and all toward the center of our galaxy. This Euclidean image covers 51 known planetary systems – and will help study many more to be discovered.”
Measuring the masses of planets
Although detecting the microlensing phenomenon requires several weeks of observations – meaning that Euclid was unable to identify any novel events during his relatively brief observing campaign – this image is so valuable because it provides the data needed to measure the masses of already known planets, as well as planets that have yet to be discovered.
“Within 24 hours, Euclid had already captured stars involved in all future microlensing events that the Roman space telescope will detect, but before the stars and planets involved had aligned,” Natalia Rektsini, who led the data release, said in a press release. (The Nancy Grace Roman space telescope is scheduled to launch later this year.) “This means that anyone who detects a microlensing event in the same region, for example with Roman, will now be able to use the Euclidean data as a reference to a time in the past and see what the stars looked like before they overlapped.”
As a result, Euclid’s observations will serve as a reference archive for future missions, enabling more detailed studies of exoplanets and more right measurements of their masses.
“In just 24 hours, Euclid provided unique data on the center of the Milky Way, giving a large and sharp image of this region,” Valeria Pettorino, ESA project scientist Euclid, said in a press note. “This data can also be used for other scientific applications, from brown dwarfs and binary stars to stellar motions and dust in our galaxy.”
This story originally appeared on WIRED Italy and was translated from Italian.