The galaxy is becoming a darker place. Galaxies are forming fewer stars than it did over 8 billion years ago and scientists are pointing to the mysterious dark matter as the culprit.

A team led by CSIRO astrophysicist, Robert Braun, said the star formation peaked over 8 to 10 billion years ago and then began to decline. The galaxies are running out of molecular hydrogen gas from which stars are made.

"If every galaxy today continues forming stars at the current rate, in one to two billion years it will be all over. Nor more stars will be formed," said Dr. Braun.

The team based this prediction of a starless future by observing 11 rare Ultra-Luminous Infra-Red Galaxies using CSIRO's Mopra radio telescope near Coonabarabran, NSW. The team of scientists from CSIRO Astronomy and Space Science from the University of Western Australia, and the Paris Observatory, compared data from galaxies that existed three and five billion years ago with those of today and found that today's galaxies had less hydrogen.

The group's findings, published today in the monthly notices of the Royal Astronomical Society, said that hydrogen has plummeted by a factor of 10 over the past five billion years.

"Today, it's become more and more difficult for the gas to fall in,'' he said. ''Our results help us understand why the lights are going out.''

Other astronomers provided another hypothesis to the case of the missing hydrogen. According to Associate Professor Hopkins, hydrogen can be found in different types and masses of galaxies over time.

"My hypothesis is we're looking in the wrong places," he said, adding that Dr. Braun's group looked exclusively at massive galaxies.

Dr. Braun blames the hypothetical dark energy that drives galaxies apart for the missing gas.

"This accelerating expansion could have made it increasingly difficult for galaxies to capture the additional gas they need to fuel future generations of star formation," he said.