Skywatchers lucky enough to have no cloud cover witnessed a rare space spectacle that no one alive today is likely to see again.
The Transit of Venus, when Venus moves directly between the Earth and the Sun, has occurred only a handful of times since the invention of the telescope in 1631, and is not due to occur again for 105 years.
Starting at 2200GMT last night, the hot planet was visible to the unaided eye for nearly seven hours, showing up as a black dot gliding slowly across the solar backdrop.
The extraordinary event was visible first from the Pacific and north and central America. Australia presented one of the best vantage points.
For Europe, the Middle East and South Asia, most of the event happened overnight, and impatient planetary observers had to wait until sunrise to observe the transit’s final moments.
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“After today, that’s it. Probably no-one alive is going to see one of these again,” said Robert Massey of the Royal Astronomical Society, after witnessing the event from the Cotswolds in southwest England.
“For most of us, this was the last chance. I was very lucky; we didn’t have very good weather but we actually managed to have a few holes in the clouds.”
Astronomers on all seven continents were planning to use the seldom-seen display to gather measurements that could help to detect more planets that exist beyond the solar system - just as Captain James Cook and other surveyors collected data during the transit in 1769 from the Pacific island of Tahiti that helped to measure the size of the solar system.
The planet named for the Roman goddess of beauty and love only rarely moves in a direct line between the Earth and the Sun. Only six transits have been observed since the telescope was invented: in 1639, 1761, 1769, 1874, 1882 and 2004, happening in pairs, eight years apart.
Cloud cover spoiled the rare opportunity for many around the world.
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“I saw it for about, maybe at most 30 seconds to a minute once, and briefly for about 10 seconds after that. It wasn’t the best view I’ve ever had, so I was delighted to see something,” said Mr Massey.
“We regrettably saw nothing from Paris. It is the hard life of the astronomer,” lamented Claude Catala, director of the Paris Observatory.
Sydney Observatory held a sell-out viewing with 1,500 people buying tickets.
About 600 people gathered at the Goddard Space Flight Center in the US state of Maryland to observe the planet also known as the Evening Star or Morning Star due to the bright sunlight it reflects early and late in the day.
In Tahiti in French Polynesia, one of the best viewing spots, up to 2,000 people gathered on the beach at Venus Point, so named for the place where Captain Cook observed the transit in 1769.
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Hakan Svedhem, a European Space Agency (ESA) scientist, observed the passage from Svalbard, Norway, a point so far north that the Sun doesn’t set in summer.
“It was a long night but it was very exciting and it was particularly nice to see it against the midnight Sun,” he said, an hour after Venus slid off the solar disc at around 0500 GMT.
“It is a very spectacular sight to see.”
Astronomers in 148 countries observed the event, including those at the world’s largest observatory atop Mauna Kea, a 4,205m (13,796ft) volcano in Hawaii. The transit was webcast by scores of observatories and space institutions.
The robotic Kepler spacecraft, a deep space planet-hunter 92 million miles away, and Nasa’s Hubble Space Telescope, orbiting 350 miles high, were monitoring the transit. Hubble used the Moon like a mirror to watch the spectacle, to avoid its sensitive instrumentation being damaged by the Sun’s rays.
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The European Space Agency’s Venus Express spaceship was orbiting Venus as it made its historic solar trek, and used the unique opportunity to study Venus’ atmosphere.
“We can learn how to observe atmosphere on planets around other stars” similar to our Sun, to determine whether they may be able to sustain life, said Mr Svedhem.
Astronauts at the International Space Station 250 miles above the Earth became the first people ever to watch a transit from space. During the 2004 occurrence they were unable to observe it because there were no filters on board.
Don Pettit, one of the crew, took photographs through optical grade windows in the station’s cupola, an observatory that gives a wide-angle view of the cosmos.
“I don’t think James Cook should be too envious,” said Mario Runco, a fellow astronaut at Johnson Space Centre in Houston, Texas. “After all, he did get an all expenses paid trip to Tahiti out of the deal.”
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Venus is the second planet from the Sun, roughly the size of the earth, with no oceans and a lead-melting surface temperature.
Swetta Jumaani, an Indian numerologist, said the event was an auspicious one, describing Venus as the planet governing love, peace, harmony and good luck. “This transit across the sun will bring good luck and good fortune this year,” she said.