Many MindedEuclid's first big release catalogues 900 million galaxies
The European Space Agency's Euclid mission has put out its first major data release. It identifies more than 900 million galaxies and over 60 million potential quasars, the bright objects powered by supermassive black holes at the centres of distant galaxies. The release covers about 14% of the total sky area Euclid will eventually map.
Euclid launched in July 2023 to build the largest 3D map of the universe, spanning about a third of the sky and over 10 billion years of cosmic history. Its target is the nature of dark energy and dark matter, thought to make up roughly 70% and 25% of the universe. Andy Taylor of the University of Edinburgh, who leads the UK science ground segment, contrasts it with Hubble: Hubble has high resolution but covers less sky, while Euclid keeps high resolution across huge volumes.
One early result is strong gravitational lensing, where a foreground galaxy bends light from a more distant one into arcs or rings, an effect dark matter boosts. The release holds about 15,000 probable cases, against roughly 1,000 known before. Taylor estimates about 170,000 will be found by the end of the mission. Lensing shows how dark matter clumps, which could help rule out theories about its nature.
This does not change what basic needs cost. Its value is in knowledge: a vast, high-resolution survey made available for researchers to work with widens the shared scientific commons, and the more people can examine it, the more questions it can answer.
The caveats are real. The lenses are candidates, not confirmed. Stephen Serjeant of the Open University calls a dark matter breakthrough from strong lensing likely but not certain, and the 170,000 figure is an estimate. A further release, with galaxy distribution and weak lensing results that map where dark matter lies, is expected next summer.
Source: Guardian