ESA Releases Euclid Data on More Than 900 Million Galaxies
The European Space Agency has published its largest batch of Euclid telescope data so far: 13 months of observations covering more than 900 million galaxies and 1.7 petabytes. Scientists hope the survey will explain dark matter and dark energy.
The European Space Agency released its first big collection of data from the Euclid space telescope on Thursday, covering observations of more than 900 million galaxies. The Euclid mission data release spans about 13 months of observing and totals 1.7 petabytes, or 1.7 million gigabytes.
The survey area equals about 9,500 times the size of the moon as seen from Earth. Euclid, launched from Florida in 2023, aims to finish the largest three-dimensional atlas of the cosmos in 2031, covering more than a third of the sky.
What the data covers
Earlier Euclid releases covered only a few days of observations. This one holds more than a year of data. It still spans only 14 per cent of the total sky area Euclid will survey in visible and near-infrared light over six years.
ESA says the release will be completed next year with the first results on dark energy and dark matter.
"It marks a major milestone for ESA's Euclid mission and for everyone involved," said astrophysicist Valeria Pettorino, ESA's Euclid project scientist.
Why dark matter and dark energy matter
Ordinary matter, meaning stars, planets, gas and dust, makes up about 5 per cent of the universe. Dark matter, known from its gravitational effects on galactic scales, may account for about 27 per cent. Dark energy, thought to drive the accelerating expansion of the universe, may make up 68 per cent.
Neither dark component emits or absorbs light, so neither can be observed directly.
Euclid tackles the problem by measuring distances as well as taking pictures. "This will tell us where galaxies are in space and time, across 10 billion years, and in all directions beyond our galactic plane," Pettorino said.
Galaxies cluster along filaments around empty space, forming what scientists call the cosmic web. Pettorino said the number of clusters and voids, and how fast the web changed, depend on the properties of dark energy and dark matter.
Gravitational lenses
Light from distant galaxies can be bent by matter in the foreground, an effect called gravitational lensing. The nearer galaxy's gravity warps the light coming from the one behind it. Researchers use the effect to study how dark matter is distributed.
The new data includes about 15,000 strong gravitational lens candidates. That exceeds the total discovered in the previous half century.
"Gravitational lenses are nature's own weighing scales," said Natalie Lines, a doctoral student in astrophysics at the University of Portsmouth in England and a member of the Euclid Consortium of scientists.
