STAFF and students at Guisborough's Prior Pursglove College are praying for blue skies on Tuesday so that they can witness an extremely rare celestial event.

The planet Venus is due to drift across the face of the sun and Earth between 6am and 12.30 and the college has acquired a solarscope to view its course.

A Transit of Venus is so rare that no human now alive has witnessed it.

Science technician Gayner Mosely said: "When I heard about this rare opportunity several months ago, I started experimenting with binoculars and filters. It worked, but was very Heath Robinson, so I was really pleased when Steve Hunnisett, director of curriculum at the college, tracked down a solarscope which will give us an inverted image of Venus moving across the sun."

Prior Pursglove has a long-standing interest in space and things celestial. Steve Hunnisett was instrumental in bringing Russian cosmonauts to Cleveland for the first time in November 1998, and the college was also involved in their last visit in October last year.

The Transit of Venus which took place in June 1769 was recorded by Captain Cook, who sailed to Tahiti in the Bark Endeavour to record the moment.

A display at the Captain Cook Schoolroom Museum in Great Ayton packs a wealth of material into a small space, outlining some of the history and science concerning the occasion.

It includes the Cook connection, present-day knowledge about Venus and how to safely view the transit - people are warned not to look directly at the sun as it could damage their eyes.

There is a list of venues in the area where telescopes are being set up to project images on to large screens. If the sky is cloudy, some centres can beam in images from elsewhere in Europe where skies are clear.

Cook's journey to Tahiti took more than seven months. On show are extracts from his journals.

Cook was a good mathematician and a meticulous observer. His measurements of the Transit of Venus were used, with those from three other sites, to find the distance of the earth from the sun.

These averaged 93,726,900 miles, well within today's limits. Further fascinating details are given of ingeniously-constructed instrumentation used in those days for astronomical measurements.

The exhibition moves into this century with images of Venus printed off the web. The museum is open daily, including weekends, 1-4pm, and the display is scheduled to the end of June. For more details, ring 01642 724296.