Galaxies older than previously thought

The William Herschel telescope in the Canary Islands reveals far-off galaxies

By BBC News Online's Anne Lavery

The oldest galaxies may have formed billions of years earlier than previously thought, according to new evidence from astronomers at Durham University, UK.

This latest data could force theorists to rethink their ideas on how galaxies were formed.

Due to the expansion of the Universe, the further away galaxies are, the faster they appear to be moving away from us. The greater the speed, the greater the Doppler Effect shifts their light towards the red end of the spectrum.

By measuring this so called redshift, astronomers are able to calculate roughly how far away the galaxy is, and therefore how long it has taken the light to reach Earth - which in turn gives its age.

Until now, astronomers thought that galaxies were formed relatively late in the history of the Universe with most galaxies having a redshift of around one.

But the Durham researchers told the General Assembly of the International Astronomical Union in Manchester, UK, that they had found a number of galaxies with a redshift as high as five or six.

This means the galaxies were already in existence about 10 billion years ago, when the Universe was six times smaller than it is now.

Final frontier

Researchers Dr Tom Shanks and Dr Nigel Metcalfe studied galaxies in a very small patch of the sky using three different telescopes. They found as many of these older galaxies had a redshift of six as already known younger ones.

This will pose a challenge to the popular theory that galaxies were formed relatively recently, predicting that hardly any galaxies should be seen with high redshifts.

Dr Shanks said the new images extend the search for galaxies to higher redshifts than ever before.

"Four years ago, we described the galaxies we found with redshifts of two as being at 'The Final Frontier' because we thought that just beyond them we might be looking back to a time before galaxies formed," said Dr Shanks.

"Now that large numbers of galaxies at even higher redshifts have been found, we feel entitled to describe them as being 'Beyond the Final Frontier.'"