Meet the real Lords of the Rings. These images, released today, show four of more than 20 highly unusual galaxies spied recently by NASA's Galaxy Evolution Explorer spacecraft, with follow-up observations by the Hubble Space Telescope. The galaxies, averaging about 10 billion years in age, are so old that standard theory dictates they can no longer spawn many new stars. But the rings, visible only in ultraviolet light (blue), say otherwise. They're so big—each would easily encircle the Milky Way—and energetic that astronomers say they must be the byproducts of enormous bursts of starmaking. Thus far, the only plausible explanation is that the galaxies in question must have somehow siphoned off enough gas from the intergalactic medium to spark the renewed activity. But such a phenomenon has never been observed before, so the rings will require more detailed study.
See more ScienceShots .