UK astronomers have discovered the most distant cluster of galaxies ever seen by peering back in time nearly ten billion years. They found hundreds of the “star cities” gathered inside a cloud of gas heated to more than 10 million degrees, it was revealed today.

The team, from universities across England plus Edinburgh, discovered the cluster using a European X-ray satellite called XMM Newton. They labelled it XMMXCS 2215-1738 then measured its distance with a giant telescope on Hawaii, the American Astronomical Society’s annual meeting at Calgary, Canada, was told.

But the scientists say they are baffled as to how such a huge cluster of galaxies, more than 500 trillion times as massive as the sun, formed so early in the life of the universe. Co-discoverer Professor Bob Nichol, from the University of Portsmouth, said yesterday: “The key question is, what’s it doing there? This massive lump of matter is three-quarters the way back to the Big Bang.”

The astronomers are now using the Hubble space telescope to take detailed pictures of the galaxy cluster.

The UK contributors included astronomers from universities in Sussex, Edinburgh, Liverpool, Oxford, Portsmouth and Nottingham. They were working with Adam Stanford, research scientist at the University of California.

American scientists have used natural “cosmic telescopes” to look back even further in time, the meeting heard. They have spotted infant galaxies born in the first billion years after the Big Bang. The star cities’ feeble light has taken an incredible 12 billion years to reach us. They were only seen because much closer clusters of galaxies acted like giant magnifying glasses on them.

The phenomenon, called a gravitational lens, was predicted by Einstein and made the distant galaxies appear up to 100 times bigger and brighter. The discovery team, led by Professor Holland Ford of Johns Hopkins University, Maryland, found them by comparing photos taken with the Hubble space telescope with infrared images taken at mountaintop observatories.

A third team, from California and Florida, has also found galaxies galore, the meeting learned. They used Nasa’s Spitzer Space Telescope to discover nearly 300 clusters of galaxies. Nearly 100 of these are between eight and ten billion light-years away, so appear as they did when the universe was less than half its present age.

The colour image, showing the faint red galaxies of the galaxy cluster XMMXCS 2215-1738 in the center, enveloped in the bluish haze representing the invisible X-ray emission from the extremely hot gas, is reprioduced courtesy the European Southern Observatory Imaging Survey; NOAO.