The $1.4 billion Euclid Space Telescope captured an Einstein ring in one of its early test images. This ring is located in the NGC 6505 galaxy, about 590 million light-years away from Earth. It is formed by the accidental distortion of light by the gravitational field as it travels through the universe.
Euclid's high-resolution imaging allows this distant (although cosmically close) ring to be well resolved and demonstrates the power of the telescope. The team's description of the ring was published in Astronomy & Astrophysics.
"All strong lenses are special because they are very rare and very useful scientifically," Conor O'Riordan, an astrophysicist at the Max Planck Institute for Astrophysics and lead author of the study, said in an ESA press release. "This one is particularly special because it is so close to Earth and the arrangement makes it very beautiful." "
Einstein loops are gravitational lenses, or regions of space-time where gravitational fields bend and refocus light. To an observer (such as a space telescope), the light is amplified, making distant light sources more visible. However, gravitational lenses also distort the light that passes through the lens, often twisting the light into lines or arcs. An Einstein ring is a rare type of gravitational lens in which light is twisted into a complete ring.
Astronomers have discovered many Einstein rings; the Webb Space Telescope and the Nordic Optical Telescope revealed the first Einstein ring in November 2024, and in April 2024, a different research team found strong evidence of dark matter in an Einstein ring formed by a distant quasar.
Scientists have known about the galaxy where Euclid discovered Einstein's rings since 1884, but the rings had never been discovered. It's a reminder of how many cosmic discoveries are hiding in plain sight, waiting to be discovered with our more advanced instruments.
The first scientific images of Euclid released in November 2023 demonstrate the power of this space telescope, which is comparable to the Webb Telescope in the deep space field. But their scientific goals are different; Webb is studying every stage of the universe, including the earliest light we can detect, to understand everything from the first galaxies to the evolution of the solar system. Euclid, on the other hand, specializes in studying the so-called dark universe - about 95% of the universe that scientists attribute to hitherto undiscovered matter and phenomena known as dark matter and dark energy.
In May 2024, the Euclid team released additional images taken during just 24 hours of Euclid observations. The images are four times clearer than those taken by ground-based telescopes and include the largest space images ever taken from space.
Speaking of Euclid's big image: In October, ESA scientists revealed a huge 208-billion-pixel image, which contains about 14 million galaxies taken by Euclid through 260 independent observations. This image will eventually become part of the largest three-dimensional map of the universe ever created. This mosaic image is just 1% of Euclid's vast observations, which will include billions of galaxies, including many from the ancient universe.
According to the same press release, fewer than 1,000 strong lenses are known so far, but Euclid is expected to discover about 100,000 during its mission. If this ring is any indication, Euclid will have great potential, and space enthusiasts will be the beneficiaries.