ORCs are vast radio bubbles that engulf many galaxies within them. Thanks to XMM-Newton, astronomers may know the powerful event that gave rise to the Cloverleaf ORC.
X-ray spacecraft reveals odd 'Cloverleaf' radio circle in new light (image) yahoo.com - get the latest breaking news, showbiz & celebrity photos, sport news & rumours, viral videos and top stories from yahoo.com Daily Mail and Mail on Sunday newspapers.