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This image may look like a celestial constellation, but in fact it is a collection of cells that would fit in a Petri dish.

The heart muscle cells were grown from stem cells in a laboratory at Imperial College London. The photograph was taken by a research group at the British Heart Foundation Centre of Research Excellence, whose members include Gabor Foldes, Sian Harding, Michael Schneider and Nadire Ali.

It was runner-up in this year's Reflections of Research, an annual competition to find the best images taken by BHF-funded scientists.