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Euclid captured over a billion galaxies in unprecedented detail, nrc.nl reported on Thursday launching a six-year mission to map the universe in three dimensions.
The European Space Agency telescope started its enormous task after launching in 2023, aiming to photograph more than anderhalf miljard sterrenstelsels. This first data release reveals faint gas streams at the edges of the Milky Way and distant spiral galaxies like M81, located twaalf miljoen lichtjaar away. The mosaic covers a massive expanse of the northern sky, capturing celestial objects with a sensitivity that distinguishes individual stars inside distant galactic arms.
Astronomers need this expansive cosmic map to investigate two invisible components that dominate the standard model of cosmology: dark matter and dark energy. Both remain fundamentally mysterious, with scientists tracking their presence only indirectly through the clumpiness of the cosmic web.
The telescope’s wide-angle lens allows it to survey a patch of the sky one hundred times larger than the view of the James Webb Space Telescope. Henk Hoekstra, a cosmologist at Leiden University and a participant in the project for roughly 15 years, told nrc.nl that the instrument achieves in a week what the Hubble Space Telescope surveyed across 36 years.
Gravitational Lensing
Einstein’s general relativity predicted that massive objects bend light, and Euclid has magnified thousands of such cosmic lenses. The count of known gravitational lenses jumps from several hundred to nearly twenty thousand in this initial dataset, according to nrc.nl. These lenses produce distorted ghost images and partial Einstein rings where background light is smeared into a circular arc.
Weak lensing effects are central to the mission, where intervening matter subtly distorts the shapes of countless background galaxies. Hoekstra compared this technique to looking at coins on the bottom of a swimming pool.
“If the pool a little bit waves, the coins seem to change shape,” Hoekstra told nrc.nl, explaining that researchers observe those distorted shapes to understand the intervening matter distribution. This statistical approach helps map the large-scale architecture of the universe.
Theoretical physicist Alessandra Silvestri, also a professor at Leiden University and a scientific coordinator for the mission, emphasized the importance of this massive catalog. “Aankomende zomer we publish our analysis of these first 3D maps, as an important test of our cosmological standard model,” Silvestri told nrc.nl. She said that the decades-old model now creaks under new scrutiny.
International Collaboration
The roughly tweeduizend-scientist consortium involves a prominent Dutch contingent spanning multiple institutions. Guadalupe Cañas Herrera, a cosmologist working in the Netherlands for over a decade, described the release as an emotional milestone. “The telescope to which we dedicate our lives exceeds all our expectations,” Cañas Herrera told nrc.nl.
Researchers plan to publish their detailed analyses of these initial three-dimensional maps in the coming summer. The overarching question of whether dark energy acts as a constant cosmological force or changes as the universe expands remains open for Euclid to answer.
Earlier coverage: Euclid Space Telescope Releases Billion-Object Map to Probe Dark Universe
