Tuesday, April 12, 2005

Earth's Oldest Object On Display

The zircon grain is barely two human hairs in diameter

A tiny crystal thought to be the oldest object on Earth has gone on public display for one day only in the US state of Wisconsin.

The 4.4-billion-year-old zircon crystal, barely two human hairs wide, was brought out at the University of Wisconsin-Madison on Saturday.

The zircon, found in Australia in 2001, led to a reappraisal of early Earth.

Analytical work by geophysicist Professor John Valley at the university in Madison, Wisconsin, showed the crystal could only have formed in a low-temperature environment.

That suggested the early Earth was much cooler than previously thought, meaning life-forming elements such as oceans were formed earlier, too.