Green mystery blob

A strange green blob in the nearby universe may be a 'light echo' from a long-dead quasar – an extremely bright object powered by a colossal black hole. Future studies of the blob could give astronomers insight into the quasar's dying days.

For months, astronomers have been working to pinpoint what illuminates 'Hanny's Voorwerp', a mysteriously lit cloud that sits close to a spiral galaxy 700 million light years from Earth.

'Voorwerp' is Dutch for 'object', and 'Hanny' refers to Hanny van Arkel, a Dutch school teacher. She found the blob as she was classifying galaxy shapes from astronomical images as part of the online Galaxy Zoo project, which aims to harness the power of volunteers to answer cosmological questions.

To find a light source for the cloud, astronomers turned to NASA's Swift satellite to look for X-ray evidence of nearby energy sources. But the search came up dry.

space.newscientist.com...