The map has a few puzzles within it. Some areas show clumps of dark matter that aren't accompanied by the bright features associated with conventional, visible material (made of baryonic matter), and vice versa.

"On the large scale the general picture is as expected, but there are some small-scale discrepancies," Richard Massey at the California Institute of Technology, Pasadena, and one of the team members who pieced together the map from hundreds of slightly overlapping images from the Hubble Space Telescope's Cosmic Evolution Survey was quoted as saying.

"The existence of large clumps of isolated dark matter and visible matter flies in the face of everything we know," said cosmologist Carlos Frenk of the University of Durham, UK.

The discrepancies, Nature says, could be a simple error resulting from the way the observations were made. But if they are real, says Massey, they will bring a huge shock