Odd Radio Circle
In astronomy, an Odd radio circle is a very large unexplained astronomical object that, at radio wavelengths, is highly circular and brighter along its edges. As of 26 June 2020, there have been four such objects observed. The observed ORCs are bright at radio wavelengths, but are not visible at visible, infrared or X-ray wavelengths. Two of the ORCs contain optical galaxies in their centers suggesting that the galaxies might have formed these objects.
