Here’s the closest ‘look’ yet at dark matter in a massive galaxy cluster. Dark matter is that stuff that astronomers cannot see but know must exist, because without its gravitational glue to hold galaxies together, they would fly apart into pieces. Naturally, spotting dark matter is a hard thing to do, because it’s, well…invisible.

A team led by Meghan Gray, of the University of Nottingham, and Catherine Heymans, of the University of British Columbia, used gravitational lensing – the same trick described below – to measure how dark matter in space distorts the light from a massive cluster of galaxies known as Abell 901/902. This is a big thing: more than 2.6 billion light-years away, it measures a whopping 16 million light-years across and is composed of more than a thousand galaxies.

The concentrations of pink stuff shows where the dark matter lies. For more images see the main Hubble press release site here.