By Paul Rincon
Science reporter, BBC News, Austin
Astronomers have revealed the effects of unseen dark matter as it tugs on galaxies in a crowded supercluster.
Dark matter acts as invisible cosmic "scaffolding" upon which visible stars and galaxies are assembled.
The dark matter in this instance has pooled into four dense clumps, in which hundreds of old galaxies are embedded.
Using the Hubble Space Telescope, a team of scientists mapped the dark matter at a better resolution than has ever been achieved before.
Co-author Catherine Heymans, of the University of British Columbia in Canada, said the survey covered one of the largest patches of sky to be observed by Hubble.
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http://news.bbc.co.uk/2/hi/science/nature/7187026.stm