The Euclid Space Telescope has made an exciting discovery—a new Einstein ring in the nearby galaxy NGC 6505, located 590 million light-years from Earth. 

• This rare celestial phenomenon, now called Altieri’s Ring, was first noticed in September 2023 by astronomer Bruno Altieri in an early, unfocused image from Euclid.

About Euclid Space Telescope

• The Euclid Space Telescope is a European Space Agency (ESA) mission, launched on July 1, 2023.
• It was launched to study dark matter and dark energy—two of the most mysterious components of the universe. 
• It aims to create a 3D map of the universe, covering billions of galaxies up to 10 billion light-years away.

Significance of the Euclid Mission

• Deepens Our Understanding of the Cosmos: Helps solve fundamental questions about dark energy and the universe’s fate.
• Largest Cosmic Map Ever Created: Covers 10 billion years of cosmic history.
• Supports Future Astronomy Missions: Complements NASA’s James Webb Space Telescope (JWST) and ESA’s Gaia mission.

What is an Einstein Ring?

• Over a century ago, Albert Einstein predicted that massive objects, like galaxies or galaxy clusters, can bend light from distant objects due to their gravitational pull. 
• This effect, known as gravitational lensing, can create arc-like or circular patterns of light around the foreground object. 
• When the alignment between the observer, the lens, and the distant object is nearly perfect, the result is a complete circle of light called an Einstein ring.
• It Is Not visible to the naked eye, can only be observed through powerful space telescopes like Euclid.

Einstein rings are scientifically valuable because they

• Help study dark matter by revealing how mass is distributed in the foreground galaxy.
• Provide insights into the expansion of the universe and test Einstein’s General Theory of Relativity.
• Allow astronomers to observe distant galaxies that would otherwise be hidden.

Einstein Cross The Einstein Cross is a rare and visually striking example of gravitational lensing. It occurs when a massive object, like a galaxy, bends and distorts the light from a more distant object behind it, creating multiple images of the background object. The first Einstein Cross, known as Q2237+030 or Huchra’s Lens, was discovered in 1985.  It is located in the constellation Pegasus, about 8 billion light-years from Earth.

The Discovery of Altieri’s Ring

• The discovery was made by astronomer Bruno Altieri in September 2023, just two months after the Euclid telescope was launched. 
• Initially, the image of NGC 6505 was blurry, as it was taken during the testing phase of the mission. 
  • However, subsequent focused images confirmed the presence of the Einstein ring, which has since been named Altieri’s ring in his honor.
• The ring is formed by the distorted light of a galaxy located 4.5 billion light-years behind NGC 6505. 

Why is Altieri’s Ring Special?

• Proximity: Most Einstein rings are found much farther away, but Altieri’s Ring is one of the closest ever observed. Only five other gravitational lenses have been found at a similar distance.
• A New View of an Old Galaxy: The foreground galaxy, NGC 6505, has been known to astronomers since the 19th century. Yet, Euclid’s advanced instruments revealed the Einstein ring for the first time.
• Distant Background Galaxy: The light forming the ring comes from a galaxy 4.5 billion light-years away, which is no longer forming new stars.