Thursday, December 10, 2009

American and European scientists say the upgraded Hubble space telescope has spotted the oldest galaxies ever seen. The images were taken with the telescope’s new Wide Field Camera 3 (WFC3) in August this year.

The galaxies are about 13 billion light years from Earth, meaning they formed less than one billion years after the Big Bang — the cosmological model of the initial conditions and subsequent development of the universe.

WFC3 was installed in May this year, during a mission by the space shuttle Atlantis to repair and upgrade Hubble. Experts say the new instrument will let them peer even further back in time, to when the universe was in its infancy. The more distant a galaxy is, the more its light is “redshifted” due to expansion of the universe. Light from the furthest galaxies is shifted to infrared wavelengths invisible to the human eye, but WFC3 can detect these.

The new image was taken in August, in the same region as a 2004 visible light image known as the Hubble Ultra Deep Field. The 2004 photo previously showed the most distant galaxies, but the new infrared pictures from the WFC3 allow even more remote galaxies to be seen.

Capturing the image took four days, and the total exposure lasted 173,000 seconds. In the three months since, twelve scientific papers have been submitted on it. On Tuesday one of these confirmed the galaxies as the furthest ever seen.

They are also the oldest, with the light from them having taken around 13 billion years to reach Earth.

“At these distances, you’re really looking back in time, like you have a time machine,” said Ray Villard, of the Space Telescope Science Institute in Baltimore. “Those things don’t exist anymore.”

The photo could be one of the ultimate achievements of the Hubble telescope, now almost twenty years old.

“These new observations are likely to be the most sensitive images Hubble will ever take,” said Professor Jim Dunlop of the University of Edinburgh.

The servicing mission in May extended the telescope’s life by around five years, but it is scheduled to be replaced by the James Webb Space Telescope in 2014. This will use infrared imaging and have a greater collecting area than Hubble, and it is thought that it may be able make out objects from just 100 million years after the Big Bang.

“We’ve really pushed Hubble to its limits,” said Villard, “and we need a bigger space telescope to go back even farther. It shows us there are really exciting things to look for with the Webb telescope.”