Just 6 years ago the first one was discovered. It happened in 2019 when astronomers identified the first ORCs, acronym for Strange Radio Circles. It is about huge, faint, annular radio-emitting structureswhich often extend between 10 and 20 times the size of our Milky Way.
Unlike ordinary galaxies, ORCs shine only in radio light, produced by magnetized relativistic plasma. Previous theories suggested that ORCs could form from shock waves released when supermassive black holes or galaxies collide. But a new study points in a different direction, linking them to superwind emanations from host spiral galaxies.
Now a team of astronomers has discovered the most distant and powerful strange radio circle ever recordeddeepening the mystery of these unusual celestial rings.
The discovery was made by scientists from the University of Mumbai using the RAD@home Astronomy Collaboratory citizen science platform, along with the Low-Frequency Array (LOFAR),the largest low frequency radio telescope in the world.
The newly identified source, RAD J131346.9+500320, is at a redshift of ~0.94, when the universe was only half its current age. This makes it the most distant and powerful ORC known to date. For added intrigue, it contains two intersecting rings, the second such case ever found.
According to Ananda Hota, founder of RAD@home, “this work demonstrates how professional astronomers and citizen scientists can, together, expand the limits of scientific discovery. “ORCs are among the strangest and most beautiful cosmic structures we have ever seen, and could hold vital clues about how galaxies and black holes co-evolve, hand in hand.”
RAD J131346.9+500320 is also the first ORC discovered by citizen scientists and the first identified with LOFAR. Its description has been published in Monthly Notices of the Royal Astronomical Society. In addition to this record-breaking ORC, two other cosmic giants were discovered. One, RAD J122622.6+640622, It spans almost three million light years, 25 times the size of the Milky Way..
Its jet curves sharply, creating a huge radius ring about 100,000 light years wide. The second, RAD J142004.0+621715, spans 1.4 million light years and also forms a striking radio ring at the end of one of its jets.
Both are located within crowded galactic clusters, where their jets likely interact with millions of degrees hot plasma, sculpting these unusual shapes. The three new objects are located in clusters with a mass of approximately 100 billion sunssuggesting that the collision of black hole jets with dense cosmic environments could be crucial in their formation.
“These discoveries – adds Pratik Dabhade, co-author of the study – demonstrate that ORCs and radio rings are not isolated curiosities, but are part of a broader family of exotic plasma structures shaped by black hole jets, winds and their environments. “The fact that citizen scientists discovered them highlights the continued importance of human pattern recognition, even in the age of machine learning.”
Future telescopes, such as the Square Kilometer Array, are expected to reveal many more ORCs. Combined with surveys like DESI and the Rubin Observatory’s LSST, astronomers hope to finally trace how these strange rings arise and evolve. For now, the latest discoveries represent a breakthrough, driven not by machines, but by human curiosity.