The European Space Agency has published its first major data release from the Euclid space telescope, a dataset comprising observations of more than 900 million galaxies. According to Asharq Al-Awsat, this initial collection spans approximately 13 months of observations and totals 1.7 petabytes of information. The survey area covers roughly 9,500 times the apparent size of the moon, representing about 14% of the total sky Euclid is scheduled to map over its six-year mission. The agency aims to complete the largest-ever three-dimensional atlas of the cosmos by 2031. This release marks a substantial increase in scope compared to previous data dumps, which covered only a few days of observations, as noted in a document excerpt from Asharq Al-Awsat.
The primary scientific objective is to investigate dark matter and dark energy, which together constitute approximately 95% of the universe. Ordinary matter makes up only about 5%. Dark matter, estimated at 27%, does not emit or absorb light. Dark energy, responsible for accelerated expansion, comprises the remaining 68%. Euclid measures distances to galaxies to construct a three-dimensional map, allowing scientists to track how the cosmic web of galaxy clusters and voids has evolved over the last 10 billion years. The exact configuration of this web depends on the properties of these invisible components.
One key method is gravitational lensing, where foreground matter bends light from distant galaxies. The new dataset includes approximately 15,000 strong gravitational lens candidates, exceeding the total discovered in the previous half century. Natalie Lines, a doctoral student at the University of Portsmouth and member of the Euclid Consortium, described these lenses as nature's weighing scales. She explained that the degree of light bending reveals the amount of matter in a galaxy, including invisible dark matter. This allows researchers to study how dark matter is distributed and how galaxies form over cosmic time.
The telescope’s ability to capture sharp images over vast areas is crucial for identifying rare phenomena. While ground-based telescopes are limited by atmospheric blur and space telescopes like Hubble cover only small patches, Euclid combines wide coverage with high resolution. The mission has also identified 60 million quasars, the bright cores of galaxies powered by supermassive black holes. Some date back to when the universe was only 5% of its current age. The first results on dark energy and dark matter are expected next year.