By observing a high-speed component of a massive galaxy cluster, Caltech/JPL scientists and collaborators have detected for the first time in an individual object the kinetic Sunyaev-Zel'dovich effect, a change in the cosmic microwave background caused by its interaction with massive moving objects.
The NASA/ESA Hubble Space Telescope has captured the best ever image of the globular cluster Messier 15, a gathering of very old stars that orbits the centre of the Milky Way. This glittering cluster contains over 100 000 stars, and could also hide a rare type of black hole at its center.
Astronomers have, for the first time, spotted planets orbiting sun-like stars in a crowded cluster - the best evidence yet that planets can form in dense stellar environments.
One of the most widely-studied of all globular star clusters appears nevertheless to harbor a mystery - a star which apparently possesses the secret of eternal youth.
Since the 2010 discovery of four stars 300 times as massive as our sun, astronomers have been scratching their heads over how they could have come to exist.
ESA has recovered a crucial science package on its Cluster mission, using a series of commands invented for the occasion.
Astronomers are studying what they decribe as one of the most complex and dramatic collisions between galaxy clusters ever seen, and which has taken 350 million years to play out.