The European Space Agency (ESA) has unveiled a new 208-gigapixel mosaic, comprised of images captured by the Euclid mission. This mission, which includes contributions from NASA, was launched in 2023 to investigate the causes behind the accelerated expansion of the universe, a phenomenon often attributed to “dark energy.”
The release of these images took place during the International Astronautical Congress held in Milan on October 15.
The mosaic is the result of 260 observations in visible and infrared wavelengths, conducted between March 25 and April 8 of this year. In just two weeks, Euclid was able to cover 132 square degrees of the southern sky, an area more than 500 times larger than that covered by the full Moon.
This mosaic represents only 1% of the broader survey Euclid will undertake over its six-year mission. Throughout this period, the telescope will observe the shapes, distances, and movements of billions of galaxies, extending to distances greater than 10 billion light-years. These observations aim to produce the most extensive three-dimensional cosmic map ever created.
This initial section of the map encompasses approximately 100 million stars and galaxies. Of these, around 14 million galaxies are expected to be utilized by Euclid to examine the elusive effects of dark energy on the universe. Through the analysis of these galaxies, Euclid will gain valuable insights into how dark energy influences cosmic expansion, furthering our understanding of this mysterious force.
“We have already seen beautiful, high-resolution images of individual objects and groups of objects from Euclid. This new image finally gives us a taste of the enormity of the area of sky Euclid will cover, which will enable us to take detailed measurements of billions of galaxies,” said Jason Rhodes, an observational cosmologist at NASA’s Jet Propulsion Laboratory in Southern California who is the U.S. science lead for Euclid and principal investigator for NASA’s Euclid dark energy science team.
Although this section of space represents just 1% of Euclid’s overall survey area, the spacecraft’s highly sensitive cameras managed to capture a remarkable number of celestial objects with extraordinary precision.
By magnifying the image by a factor of 600, the detailed structure of a spiral galaxy within the galaxy cluster Abell 3381, located 470 million light-years away, becomes visible. This level of detail highlights the advanced capabilities of Euclid’s instruments in resolving distant cosmic structures.
“What really strikes me about these new images is the tremendous range in physical scale,” said JPL’s Mike Seiffert, project scientist for the NASA contribution to Euclid. “The images capture detail from clusters of stars near an individual galaxy to some of the largest structures in the universe. We are beginning to see the first hints of what the full Euclid data will look like when it reaches the completion of the prime survey.”
Also visible in the mosaic are clouds of gas and dust located between the stars within our own galaxy. These clouds, often referred to as “galactic cirrus” due to their resemblance to cirrus clouds on Earth, are detectable by Euclid’s visible-light camera as they reflect light from the Milky Way.
The mosaic released offers a glimpse of what is to come from Euclid. The mission plans to release 53 square degrees of the survey, including a preview of the Euclid Deep Field areas, in March 2025. The first set of cosmological data from the mission’s initial year is expected to be made public in 2026.
NASA’s upcoming Nancy Grace Roman mission will also contribute to the study of dark energy, employing approaches that complement those of Euclid. Scheduled for launch by May 2027, Roman will use Euclid’s findings to guide its own investigation into dark energy.
While Roman will cover a smaller area of the sky than Euclid, it will produce higher-resolution images of millions of galaxies, enabling a deeper exploration of the universe’s history.
Beyond dark energy research, Roman will also survey nearby galaxies, identify and study planets within the Milky Way, and investigate distant objects in the outer regions of our solar system.
