Euclid captures 60 million stars in the sharpest wide image ever of our galaxy’s core

Euclid’s visible-light camera stitched together nine individual pointings, each covering a patch of sky larger than the full Moon. The original data were captured in black and white and later colorized using archival observations from the Canada-France-Hawaii Telescope. The final mosaic is not simply beautiful — it is scientifically formidable. For comparison, Euclid’s sharpness in visible light rivals that of Hubble’s wide-field camera, but each single Euclid pointing covers 270 times more sky area. Reproducing this mosaic using the Keck Observatory would require roughly 2,000 hours of telescope time. Euclid did it in one day.

The image also reveals something that looks like empty space but is not. The dark, seemingly vacant patches scattered across the frame are dense molecular clouds — regions so thick with dust and gas that they absorb virtually all the visible light coming from behind them. In one area, newly formed massive blue stars are ionizing surrounding hydrogen gas, producing faint red glows visible in the image’s detail cutouts.

Microlensing and the hunt for cold worlds

The galactic bulge is the ideal laboratory for a planet-hunting technique called gravitational microlensing. When one star passes in front of another from our point of view, the nearer star acts as a natural gravitational lens, bending and brightening the background star’s light. If a planet orbits the foreground star, its gravity introduces a subtle asymmetry in that brightening — a tiny signal that, when detected, confirms the planet’s presence and constrains its mass.

This technique is particularly powerful for detecting cold, distant planets orbiting far from their host stars — worlds that other methods rarely find. In the last two decades, nearly 300 exoplanets have been discovered by microlensing, all toward the galactic center and all using ground-based telescopes. Euclid’s new image already contains 51 known planetary systems within its frame.

Two cold exoplanets merit special mention. OGLE-2005-BLG-390Lb is an icy planet often compared to Hoth from Star Wars, discovered 20 years ago by team member Jean-Philippe Beaulieu of the Institut d’Astrophysique de Paris. OGLE-2013-BLG-341Lb is a rarer system consisting of two stars and one planet, whose mass can now be better constrained by combining Euclid data with earlier Hubble and Keck observations.

A permanent reference for Roman and future missions

Perhaps the most remarkable aspect of this dataset is its role as a temporal anchor. In just one day of observation, Euclid captured every star that will be involved in microlensing events that NASA’s upcoming Nancy Grace Roman Space Telescope will detect — before those alignments have even occurred. The logic is elegant: by documenting the positions and brightnesses of tens of millions of stars now, astronomers will be able to compare Roman’s future observations against this baseline and measure precisely how stars have moved. That motion, over time, is what allows scientists to calculate a planet’s mass.

Natalia Rektsini of the Institut d’Astrophysique de Paris, who led the data release for the scientific community, summarized the significance clearly: Euclid’s galactic bulge dataset will serve as a time reference for past and future missions, applicable not only to exoplanets but also to binary stars, brown dwarfs, stellar motions, and the dust distribution across our galaxy.

Euclid launched in July 2023 aboard a SpaceX Falcon 9 rocket and has been stationed approximately 1.5 million kilometers from Earth on a mission to map dark matter and dark energy across one-third of the sky. This unprecedented detour toward the Milky Way’s brightest region has proven that the telescope performs equally well in conditions it was not originally designed for — and the science community is only beginning to explore what lies within those 60 million stars.

© 2026 SKYCR.ORG | Homer Dávila Gutiérrez, FRAS. All rights reserved. Total or partial reproduction is prohibited without express authorization.