He is part of a group using Hubble to explore 'gravitational lenses' - clusters of galaxies billions of light years away whose gravitational pull acts as a natural magnifying glass, bending and refocusing the light from even more distant galaxies. Studies of gravitational lenses will reveal more information about the way dark matter is distributed through the universe. Recently, Hubble has also given a more precise estimate of the age of the universe, based on its rate of expansion. And it has sent back pictures of the most distant-known galaxy, forming 1bn to 2bn years after the Big Bang around a massive black hole. The images sent back this year, after astronauts repaired the telescope's defective mirror, show a myriad of astronomical objects too distant to be seen with the most powerful Earth-bound observatories. Most troubling is their implication that the universe is only 8bn years old, when many astronomers are confident from other evidence that the oldest stars have been shining for about 15bn years. The research team found 20 individual stars of a type called Cepheid variables in the distant M100 galaxy. < But the bus-sized instrument has taken many more spectacular pictures through its new corrective lenses. Some of the best shots, released this month by the US space agency Nasa, show parts of the universe billions of light years away - and therefore billions of years in the past. Most of the stars are arranged in disorganised groups that look like torn fragments of present-day spiral galaxies but may in fact be their precursors. If so, it will lend more support to the idea of a low-density open universe with a less even distribution of matter than the popular 'flat universe' model. Yet another fragment of Hubble evidence in favour of a an ever expanding universe came in November, when astronomers published the results of a search for small dim stars, too faint to be seen from Earth, which they thought might make up some of the universe's 'missing mass'. They found far fewer than expected. Using the telescope's Faint Object Spectrograph, astronomers from the National Aeronautics and Space Administration, Johns Hopkins University in Baltimore and UC San Diego observed the spectrum of a faint quasar, called UM675, about 12 billion light years from Earth. Photo, COLOR, Saturn's Stormy Weather: A white strip on planet Saturn, seen in photo taken by Hubble Space Telescope, is believed to be a giant storm of ammonia clouds that is now several times larger than Earth. Reuters