In late 2019, the Australian Square Kilometer Array Pathfinder (ASKAP) radio telescope complex detected three unusual circular objects while collecting data to compile an Evolutionary Map of the Universe (EMU). These were three cosmic smoke rings. Another technique confirmed the existence of these objects.
The characteristics of these signals do not fit into any of the known types of studied objects. Unusual signals can only be seen in radio waves, but they are not detected in the X-ray, optical or infrared ranges.
Researchers have collected all the data from the ASKAP radio telescope and found that such circles have met in space more than a thousand times. It is not yet known at what distance from the ground they are. They have already brushed aside theories that these could be star-forming regions or supernova remnants.
Scientists are now looking around the world for radio telescopes that could continue observing strange radio circles to find an answer to the question of their origin ultimately.
One of the working versions: strange radio circles are shock waves from explosions in distant galaxies and collisions of a star and a black hole.