Astronomers have caught a galaxy cluster in the prime of its life — perhaps just before it transitions to retirement.
Astronomers have discovered a giant cosmic void that explains why our Local Group of galaxies is moving through the universe as fast as it is.
How much galaxy clusters huddle together depends in part on how fast these clusters formed — and that formation rate depends on dark matter.
In its first — and final — month of flight, the Hitomi X-ray observatory measured the calm within the bubbling core of the Perseus Cluster.
Astronomers discover a vast collection of young galaxies from the early universe.
Astronomers are peering into a galaxy cluster’s past, using Hubble’s Frontier Fields to measure the light from ghost stars cast adrift in galaxy collisions.
Dark matter in the "Train Wreck" galaxy cluster (Abell 520) appears to behave in unusual ways. Now, new Hubble images are heating up the debate.
Astronomers have mapped the cosmic watershed and discovered a massive supercluster that extends more than 500 million light-years and contains 100,000 large galaxies. The Milky Way sits on the edge of this humongous structure.
Astronomers have counted up the number of galaxy clusters in the cosmos and found a problem: the number is much lower than they expected. What's going on?
Astronomers have discovered a supermassive galaxy cluster that both meets and challenges expectations for how clusters ought to behave.
Many instruments working together have profiled a baby galaxy group, seen not long after the Big Bang, of the kind that probably evolved into our Milky Way.