Scientists have recently announced that they may have made what has to be one of the biggest underestimations on record – they think there may be close to a billion more stars than they had previously thought. So how do you miss a BILLION of anything, much less stars?
Astronomers use ultraviolet light signature to find distant stars, but it turns out that might not be the most accurate way to take a universe wide head count. Ultraviolet light from very old and very distant galaxies may be blocked by interstellar clouds of dust and gas and never reach Earth.
“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,” says Matthew Hayes of the University of Geneva’s observatory, who led the recent investigation that led to the new estimate. Hayes’ team used Europe’s Very Large Telescope (VLT) – which is actually located in Chile – to make their new guess at the number of stars that might actually be out there. The VLT is the world’s most advanced optical instrument. They swept the sky twice, first looking for traditional light signature traces, then using a special camera called HAWK-1 to look for a signature emitted on a different wavelength, known as the hydrogen-alpha line. The second sweep highlighted a great many light sources that the first, traditional sweep had missed.
Based on this new data, the team estimated that traditional surveys have only been picking up a tiny fraction of the light emitted by distant galaxies – about 10%. That leaves potentially 90% of the galaxies in the universe undiscovered and unseen.
