Counting all of those twinkling lights in the night sky just got a lot harder.
- Astronomers could have miscounted the number of galaxies in the universe.
- Old, distant galaxies are often missed because their light may be obstructed.
- The discovery could add powerfully to knowledge about the timeline by which stars and then galaxies formed.
Astronomers may have underestimated the tally of galaxies in some parts of the universe by as much as 90 percent, according to a study reported on Wednesday in Nature, the weekly British science journal.
Surveys of the cosmos are based on a signature of ultraviolet light that turns out to be a poor indicator of what's out there, its authors say.
In the case of very distant, old galaxies, the telltale light may not reach Earth as it is blocked by interstellar clouds of dust and gas -- and, as a result, these galaxies are missed by the map-makers.
"Astronomers always knew they were missing some fraction of the galaxies... but for the first time we now have a measurement. The number of missed galaxies is substantial," said Matthew Hayes of the University of Geneva's observatory, who led the investigation.