DAVID GREEN, HOST:
Let's look to the sky now. Scientists say they have found what could be the most massive cluster of galaxies ever seen. One of the galaxies is giving birth to new stars at an astonishing rate. Here's NPR's Nell Greenfieldboyce.
NELL GREENFIELDBOYCE, BYLINE: Galaxy clusters can contain hundreds to thousands of galaxies. The official name of this cluster is a bunch of letters and numbers, but scientists just call it the Phoenix Cluster, and it's over five billion light years away. Michael McDonald is an astrophysicist at MIT. He says the Phoenix Cluster isn't just big, it's unusual in other ways too. It produces more X-rays than other known cluster, and usually the centers of galaxy clusters look old and dormant, but this one is spewing out new stars at the unmatched rate of over 700 new stars per year.
MICHAEL MCDONALD: This extreme rate of star formation was really unexpected.
GREENFIELDBOYCE: He says it's nearly five times higher than the next most prolific star producer at the center of a cluster.
MCDONALD: So it's really crushing the record.
GREENFIELDBOYCE: And he says it's way faster than our own Milky Way, which produces just one to two new stars a year. The discovery is described in the journal Nature, and it should force a rethink of how galaxies and galaxies clusters evolve. Researchers have already used 10 different telescopes to peer at the Phoenix Cluster, but they hope to also take a look with the Hubble space telescope, which should let them see exactly where in this galaxy the star formation is happening. Nell Greenfieldboyce, NPR News. Transcript provided by NPR, Copyright NPR.