March 2, 2015
Peering back in time to find the very earliest objects in the universe, an international team of astronomers has discovered a galaxy that shouldn't be there at all.
The problem, the scientists report Monday in Nature, is that while the tiny galaxy dates from just 700 million years or so after the big bang, it's far more dusty than something this young and small has any right to be.
It's surprising, says Daniel Marrone, a University of Arizona expert on galaxy formation who wasn't involved in the research, because although dust is essential for the formation of planets and other solid material, the cosmos started out with no dust at all. In the aftermath of the big bang, the universe consisted only of hydrogen and helium gas (along with dark matter, but that's invisible).
The dusty galaxy is just one of the recent surprises astronomers have found. "Last week," says Marrone, "we learned of an incredibly massive black hole in the early universe. Now we have this average galaxy with significant amounts of dust. We've had this cartoon picture of the early universe, but it's clear that we really don't know what's going on."
