Hubble Telescope snaps 1st images of clashing star clusters at the hearts of dwarf galaxies / Hubble unveils first images of ongoing star cluster mergers near center of dwarf galaxies / These dwarf galaxies in the Hydra cluster are baffling scientists: 'We found something we didn't expect' / Observers investigate a nearby galaxy cluster merger / Observations confirm that early-universe quasar neighborhoods are densely populated with companion galaxies / Dark matter ghosts its way through powerful (and messy) collision of galaxy clusters / Galaxy clusters could be used as dark matter colliders to understand nature of invisible particles, say scientists / Researchers explore an old galactic open cluster / Hubble peers at pair of closely interacting galaxies / Nasa's latest image shows galaxies in 'cosmic interaction'