The image is a mosaic that includes more than 60 million stars, as well as nebulae and star clusters. This will allow scientists to confirm the possible presence of exoplanets and measure their masses with greater precision using microlensing techniques.
Euclid’s power
Although Euclid was designed to observe billions of distant galaxies, its visible-light camera is sensitive enough to identify individual stars in the center of the galaxy – a region that is extremely bright and densely populated – without being overwhelmed by the intense light.
On March 23, 2025, Euclid turned its gaze toward the Milky Way’s bulge and captured this massive image in just 26 hours of observations. The result was remarkable: a mosaic composed of nine separate “pointings” (exposures) by its visible-light camera, each covering an area of sky larger than the full moon.
While the quality of Euclid’s visible-light images is comparable to that of the Hubble Space Telescope, there is one big difference: Each point that Euclid captures in just a few hours covers an area 270 times larger than Hubble’s field of view. It is also very fast. To put this in perspective, Keck Observatory would need approximately 2,000 hours to observe the same mosaic.
image of galaxy
The new Euclid image captures more than 60 million stars along with nebulae and star clusters in one of the most crowded regions of the Milky Way – a location ideally suited for discovering exoplanets through gravitational microlensing.
“To catch microlensing, you have to observe parts of the sky that are packed with stars, such as those close to the center of our galaxy,” Jean-Philippe Beaulieu, who led the observing campaign, said in a press release. “During the past 20 years, nearly 300 exoplanets have been discovered using this technique, all with ground-based telescopes and all toward the center of our galaxy. This image from Euclid includes 51 known planetary systems – and will help study many more to be found.”
measuring planetary masses
Although detecting a microlensing event requires several weeks of observations – meaning that Euclid could not identify any new phenomena during its relatively short observing campaign – what makes this image so valuable is that it provides the data needed to measure the masses of already known planets, as well as planets that have not yet been discovered.
“In 24 hours, Euclid has already captured the stars involved in all future microlensing events that the Roman Space Telescope will detect, but before the stars and planets involved are aligned,” Natalia Rectacini, who led the publication of the data, 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 area, for example with Roman, will be able to use the Euclid data as a time reference from now to the past and see what the stars looked like before the overlap.”
In fact, Euclid’s observations will serve as a reference archive for future missions, enabling more detailed studies of exoplanets and more precise measurements of their masses.
“In just 24 hours, Euclid has provided unique data on the center of the Milky Way, with a large and clear view of this region,” Valeria Petorino, ESA’s Euclid project scientist, said in a press release. “This data can also be used for other scientific applications, from brown dwarfs and binary stars to stellar motion and dust in our galaxy.”
This story was originally published on wired italia And it has been translated from Italian.
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