It looks like an empty patch of space, but astronomers say it holds a galaxy that contains no stars. If Robert Minchin of Cardiff University in Wales and his colleagues are right, they have found the first member of a population of galaxies that theorists have proposed but observers had never seen.
In 2000, Minchin's team noticed two apparently isolated hydrogen clouds in a radio telescope survey of the Virgo Cluster of galaxies. Follow-up observations with visible-light telescopes showed that one of these clouds was associated with a faintly glowing galaxy. However, long exposures taken with the 2.5-meter, visible-light Isaac Newton Telescope in the Canary Islands offered up a surprise: The second cloud had no partner glowing galaxy.
"It's a very intriguing object," comments galaxy researcher Richard S. Ellis of the California Institute of Technology in Pasadena. "It's puzzling how this ball of hydrogen hasn't got any stars in it."
It could be that several smalle