A spectacular astronomical event so rare that no living person has witnessed it will be visible in Britain’s skies next month, when Venus moves across the face of the Sun.

At 6.19am on Tuesday June 8, shortly after sunrise, the planet will appear as a small black disc silhouetted against the Sun, as it makes its first "transit" since December 6 1882.

For the next six hours, the Earth’s nearest planetary neighbour will cut a slow left-to-right diagonal path across the southern part of the Sun, before disappearing again at 12.24pm.

Given good weather, the entire phenomenon will be observable from Britain - the first time this has happened since 1283, when no-one knew to watch for it.

While another transit will take place on June 6 2012, this will not be seen by British skywatchers, who must wait until 2247 for another chance.

Transits occur so infrequently that only five have ever been observed, and they have led directly to some of the most important discoveries in astronomy and geography.

The distance between the Sun and the Earth, 93 million miles, was first calculated with approximate accuracy during an 18th century transit, and Captain James Cook became the first European to reach Australia and New Zealand when dispatched to the South Pacific to observe the transit of 1769.

This time, scientists plan to take advantage of the rare opportunity by testing technology intended to find Earth-like planets orbiting distant stars.

When such "exosolar" planets make transits of their own parent stars, the event produces a minute dip in the brightness of that star’s light as seen from Earth.

On June 8, astronomers will turn instruments designed to measure this effect towards the Sun, to discover whether Venus’s transit affects its brightness as predicted.

"Observing the transit of Venus is very like observing the transit of planets around other stars," said Gordon Bromage, Professor of Astronomy at the University of Central Lanashire, who is co-ordinating transit events for the Royal Astronomical Society.

"We are going to be looking for planets like our own using this method, and it is a great opportunity to try things out."

Hundreds of events are being held at observatories and universities across the country to allow the public to watch the transit, which is expected to be the biggest event in popular astronomy since the total solar eclipse in 1999.

As with the solar eclipse, scientists have warned people not to look directly at the Sun during the transit, but either to use eclipse viewing glasses, or to the image of the Sun onto a screen using a small telescope.

Venus travels between the Earth and the Sun approximately once every 18 months, but this rarely produces a transit as the orbits of both planets are slightly angled. At present, transits occur at intervals of 8, 121.5, 8 and 105.5 years, and this pattern will continue until 2984.

A transit has happened just six times since the invention of the telescope in 1608 made the phenomenon predictable and observable. The event of 1631, however, which was correctly forecast by Johannes Kepler, was not visible from Europe and was thus missed by astronomers.

It was observed for the first time on November 24, 1639, by Jeremiah Horrocks, a 20-year-old self-taught Englishman, who had used Kepler’s tables to calculate that another transit was due.

A list of UK events to mark the transit, compiled The Royal Astronomical Society, is available at www.transit-of-venus.org uk, along with a downloadable diagram of the Sun during the transit.

If a telescope is used to project the Sun onto this diagram, and viewers record the precise times at which Venus moves into particular positions, it will be possible to calculate the distance to the Sun yourself.