The hunt for dark matter started with astronomer Fritz Zwicky's observations of the Coma galaxy cluster in the 1930s. This recent image of the Coma cluster combines optical and X-ray observations from the Chandra mission. J.Sanders et al/NASA/CXC/MPE/SDSS hide caption

itoggle caption J.Sanders et al/NASA/CXC/MPE/SDSS
itoggle caption Carlos H. Faham

Science has been working to shed light on the nature of the Universe for 400 years. Alberto Pomares/iStockphoto.com hide caption

itoggle caption Alberto Pomares/iStockphoto.com

This image of the galaxy cluster Abell 520 — 2.4 billion light-years away — may challenge some of our basic theories about Dark Matter. It is overlaid with false-color maps showing concentrations of starlight (orange), hot gas (green) and mass (blue). The mass is mostly Dark Matter. M.J. Jee and A. Mahdavi/NASA/ESA/CFHT/CXO hide caption

itoggle caption M.J. Jee and A. Mahdavi/NASA/ESA/CFHT/CXO