A new super telescope

Astronomers at Queen's University, Belfast, are redefining the position of the edge of the solar system using a new camera on the Isaac Newton telescope in the Canary Islands.

"There has been an explosion in our ability to detect distant objects over the past six years," said astronomer Alan Fitzsimmons. "We now know of more than 70 objects that orbit the Sun at about the distance of Pluto in the Kuiper belt."

At present, the astronomers can detect objects just 50 kilometres across and 47 times further from the Sun than the Earth. "The brightest is one million times fainter than the faintest star that you can see with the naked eye on a clear night in the countryside," said Dr Fitzsimmons.

Dr Fitzsimmons and his colleagues plan to use the upgraded telescope to identify objects even further from the Sun. "We believe that there are objects out there," he said.

By studying these distant objects, astronom-ers hope to learn more about the formation of giant planets such as Saturn and Neptune. They think the objects, which are mainly ice and organic compounds, are the rubble left over from the formation of the giant planets and that they dragged the young giant planets further from the Sun and into their present positions.

Earlier this year, astronomers discovered that the distant objects come in two varieties: red and grey. "The leading theory on why this might be is that carbon monoxide has boiled off the surfaces of the grey ones," said Dr Fitzsimmons. This would indicate that the objects had come into the inner solar system as comets. The latest data on the colour difference will be presented at a European Southern Observatory workshop organised by Dr Fitzsimmons next week.