ESA's Euclid Space Telescope Captures the Center of the Milky Way with Extremely High Resolution
The ESA's Euclid space telescope was launched on July 1, 2023, aboard a SpaceX Falcon 9 rocket. A few weeks later, the first test images captured by the new European scientific instrument were released, even though its mission was just beginning. Over the months, the telescope faced several engineering challenges, managing to capture images of an Einstein ring and various gravitational lenses, then focusing on the study of dark matter and dark energy.
The latest news from the ESA's Euclid space telescope involves a new high-resolution image of the center of the Milky Way. According to the European Space Agency, this is the largest and most detailed image ever made of the center of our galaxy using visible light. In this brilliant puzzle, 60 million stars are distributed, with many exoplanets orbiting around them. Thanks to the data related to the brightness variations of stars, it is possible to discover new ones and measure their mass (microlensing).
ESA Euclid and the Photograph of the Milky Way
The image is the result of just over a day of observations (26 hours), during which the ESA's Euclid space telescope was able to gather a vast amount of information about the galactic center. Thanks to new detection technologies, this telescope has the same sharpness and sensitivity as Hubble in the visible but covers an area 270 times larger.
[Click on the image to enlarge]
While this instrument is designed mainly to observe very distant galaxies and galaxy clusters looking for the effects of gravitational lenses, in this case, the telescope was aimed at the 'neighborhood' to observe the stars.
As explained by Jean-Philippe Beaulieu (Institut d'Astrophysique de Paris), "to capture microlensing, it is necessary to observe parts of the sky that are crowded with stars, such as near the center of our galaxy. Over the past twenty years, nearly 300 exoplanets have been discovered using this technique, all with ground-based telescopes and all towards the center of our galaxy. This image from Euclid includes 51 known planetary systems—and will help study many more that will be discovered."
The good news is that, compared to other techniques for detecting exoplanets, microlensing allows us to observe not only large hot gas giants but also cooler planets that might otherwise escape detection. In the future, the Nancy Grace Roman space telescope (RST) can use not only its own resources but also the data from the European telescope to find new exoplanets within the Milky Way.
The resultant image captured by ESA's Euclid space telescope in early 2025 and released only recently is a mosaic of 9 individual images (in a 3 x 3 configuration) covering 4.8 square degrees, which corresponds to an area that is 22 times the full Moon as observed from Earth. The VIS instrument (which observes in the visible) captured a monochromatic photograph. The visible coloration in the image was created thanks to the CFHT-Megacam telescope located in Hawaii, which employed three wideband filters.
Valeria Pettorino (Euclid project scientist at ESA) stated, "this result demonstrates what a relatively small and dedicated team can achieve within a large international mission. The team dedicated to exoplanets includes significant contributions from young researchers and has been supported by the Science Ground Segment unit working on the visible instrument. In just 24 hours, Euclid has provided unique data on the center of the Milky Way, with a wide and sharp image of this region. Over time, the separation between sources and gravitational lenses increases. That’s why this data from Euclid will serve as a time reference for past and future missions and enable studies on 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 in our galaxy."