US astronomers have discovered a huge black hole, a million times the mass of the sun, in a nearby galaxy -- a finding that could help better understand the origins of the universe.

The announcement Monday by the American Astronomical Society said the surprise discovery in a so-called "dwarf" galaxy offers evidence that black holes -- regions of space where not even light can escape -- formed before the buildup of galaxies.

"This galaxy gives us important clues about a very early phase of galaxy evolution that has not been observed before," said Amy Reines, a researcher at the University of Virginia who presented the findings to the AAS annual meeting.

The galaxy, called Henize 2-10, is 30 million light-years from Earth, has been studied for years, and is forming stars very rapidly. It resembles what scientists think were some of the first galaxies to form in the early universe.

Reines along with Gregory Sivakoff and Kelsey Johnson of the University of Virginia and the National Radio Astronomy Observatory (NRAO), and Crystal Brogan of the NRAO, observed Henize 2-10 with the National Science Foundation's Very Large Array radio telescope and with the Hubble Space Telescope.

They found a region near the center of the galaxy that strongly emits radio waves with characteristics of those emitted by super-fast "jets" of material spewed outward from areas close to a black hole.

They then searched images from the Chandra X-Ray Observatory that showed this same, radio-bright region to be strongly emitting energetic X-rays. This combination, they said, indicates an active, black-hole-powered, galactic nucleus.

"Not many dwarf galaxies are known to have massive black holes," Sivakoff said.

While black holes of roughly the same mass as the one in Henize 2-10 have been found in other galaxies, those galaxies all have much more regular shapes.

"This galaxy probably resembles those in the very young universe, when galaxies were just starting to form and were colliding frequently. All its properties, including the supermassive black hole, are giving us important new clues about how these black holes and galaxies formed at that time," Johnson said.