This gorgeus astro-soap-bubble is a freaky nebula discovered last July by Dave Jurasevich of the Mount Wilson Observatory in California, who called it the "Cygnus Bubble." New Scientist has the explanation, courtesy of Adam Frank of the University of Rochester: "'Spherical ones are very rare.' One explanation is that the image is looking down the throat of a typical cylindrical nebula. However, it is still remarkably symmetrical, Frank says."
(Image: Travis A. Rector/U of Alaska Anchorage/Heidi Schweiker/NOAO)