Researchers at CalTech recently discovered, using an experiment launched into space on one of NASA's sub-orbital rockets, that there is more cosmic light in the universe than is produced by all known galaxies. The researchers theorize that this means there may be stars in the space between galaxies that don't emit enough light to show up on our radar, but that combined still present a significant source of light. The space between the galaxies, which we currently think is dark, may actually contain weak stars that were stripped from their own galaxies and thrown farther into space.

A research paper based on these findings will be published tomorrow, November 7, in the journal Science.

The researchers estimated that about half of the stars in the universe are "orphan" stars like this, without a galaxy that they belong to. Their orphaning may have occurred when two galaxies collided. In the merging process, these stars may have been flung out into distant corners of the universe. There may be billions of stars like this in the universe.

"If this is true, then there is an entire population of stars that's been sitting out there, but because they are individually so faint we can really only see them in ensemble," said Harvey Moseley, an astrophysicist at NASA.

NASA's Spitzer Space Telescope picked up signs of this background light earlier, before the CalTech team sent the CIBER experiment up to study the stars more closely. An earlier theory proposed by researchers before this new information from CIBER was that this light was a remnant of the earliest galaxies that formed during the Big Bang.

CIBER used a highly sensitive infrared light meter to get a read on the light in the universe. The scientists learned a few things from CIBER.

"The fluctuations seem to be too bright to be coming from the first galaxies. You have to burn a large quantity of hydrogen into helium to get that much light, then you have to hide the evidence, because we don't see enough heavy elements made by stellar nucleosynthesis, which means these elements would have to disappear into black holes," said Michael Zemcov, one of the lead researchers on this project.