Scanning the dark universe, Euclid discovers a cosmic light scene Written by Katrina Miller
Euclid, the telescope launched into space by the European Space Agency (ESA) last summer, finally showed off its capabilities on Thursday, releasing a series of breathtaking images and early scientific results.
The telescope will help astronomers understand two of the universe's greatest mysteries: dark matter, the invisible glue that holds galaxies together, and dark energy, the force that pulls them apart.
“Before we can try to understand what it is, we need to understand how it behaves,” astronomer Jean-Charles Cuillandre of the CEA Paris-Saclay said of dark matter.
This mysterious substance bends and distorts light, an effect known as gravitational lensing. In extreme cases, lensing can distort galaxies and even create mirror images of a single light source.
Euclid captured this effect when he gazed at Abel 2390, a galaxy cluster 2.7 billion light years away. 90% of the mass of this star cluster is dark matter.
Gravity causes dark matter to clump together, but dark energy counters this effect. By studying the density of dark matter throughout the universe, astronomers can learn how dark energy affects the structure of the universe.
Euclid's speciality is its ability to capture large swaths of the sky in incredible detail. Galaxies close to bright stars like Beta Hohenyx may not be visible to observatories on Earth, but Euclid's keen eyes can resolve them.
The telescope's sensors are like a net that captures light, Cuirandre says. “It captures everything.”
In a series of papers, the Euclid team also announced the discovery of new dwarf galaxies, star clusters, and free-floating planets. Astronomers say these show how the mission can go beyond its core goals.
“We call it legacy science. It's something Euclid can do,” said Michael Seifert, a cosmologist working on the mission at NASA's Jet Propulsion Laboratory.
The telescope photographed these two galaxies grazing each other 62 million light-years away, producing a blurred edge and tail.
Such interactions are common: “It's very rare to find an isolated galaxy,” Dr. Quilland says, “and that's what we're finding.”
Euclid photographed the spiral galaxy NGC 6744, located 30 million light-years from Earth.
The rotation of a spiral galaxy causes interstellar gas and dust to coalesce, promoting star formation along the galaxy's arms. The blue particles in this image are hot, massive baby stars.
A nearby dwarf galaxy tore off one of NGC 6744's arms, and Dr Cuillandre said the galaxy also bears a scar. “It bears traces of what happened over a time frame of billions of years,” he said.
Euclid also focused on Messier 78, the birthplace of the star. With a near-infrared field of view, the telescope can peer through clouds of gas and dust to see the bright blue young stars hidden within.
Stars spew protons and neutrons that shape the dust and other material around them, much like winds shape clouds on Earth.
Eventually, cavities form around these stars and their light spreads throughout the universe.
The latest images come from just one day's worth of observations. “We're just getting started,” Dr. Seifert said.