Venus made a rare transit across the face of the Sun today, giving stargazers from Australia to the Middle East and Africa a celestial view that no living person had seen before.
The planet Venus passes across the front of the sun as viewed from Sydney, Australia
To the fascination of people around the globe armed for the occasion with telescopes, pinhole cameras and special dark glasses, Venus appeared at 6.22 a.m. Irish times: a small black dot on the lower edge of the Sun starting its six-hour transit.
"We are watching the first transit of Venus since 1882 - until this morning no one alive has ever seen this event," said Dr Robert Massey of Britain's Royal Observatory in Greenwich as more than 100 people gathered in the courtyard of the London landmark to witness the phenomenon.
Banks of photographers with telephoto lenses and television crews captured the event. People queued patiently as parents lifted small children to gaze into telescopes set up in the courtyard of the observatory on a clear, warm morning.
Others used special glasses handed out by staff to see the event.
Scandinavian airline SAS offered dark glasses to about 3,500 travellers on Nordic flights to watch Venus from above the clouds. It was partly cloudy over sections of northern Europe.
In the Middle East, schoolchildren gathered on the hills outside Beirut to watch the passage through dark glasses. For the Americas, however, the complete transit was only partially visible.
Venusian transit only occurs four times every 243 years. Two are in December, eight years apart, and then 121.5 years later there are two June transits, also eight years apart. After another 105.5 years the cycle begins again.
The next passage will occur in 2012 but will not be visible in many parts of the world.
In the past, scientists calculated the distance of the Earth from the Sun, the astronomical unit (AU), from measurements of the duration of the transit of Venus made from widely separated latitudes.
England's Captain James Cook travelled to Tahiti on a special expedition to make observations during the 1769 transit. This time, too, observers around the world will be timing the transit and repeating the historic calculations.