The transit started at about 10.15am, with the middle of the event around 1.30pm. Venus will reach the far edge of the sun by 4.25pm and the event ends around 4.45pm.
MetService meteorologist Daniel Corbett said this afternoon it was clouding over in Auckland and Northland, and while it had been "pretty good'' around the East Coast of the North Island this morning cloud was also creeping into their skies too.
In Waikato and Taranaki there were some breaks in the cloud, allowing brief glimpses of the Transit of Venus.
But the best place to have a chance of spotting it was in Southland, Otago and Fiordland.
"They've got lovely blue sky,'' Mr Corbett said.
At the Mt John University Observatory, part-time observer Pam Kilmartin said they were receiving nice images.
"We were enviously watching down towards Twizel, because it had the sun probably most of the morning and we could see the shadow about half way down the Mackenzie plain, we had the sun behind the cloud for quite a while but now everything is nice and we can see the image of Venus on the sun.''
The observatory had not been too busy with people wanting to watch the event because snow had closed the road.
"People are walking up the hill so we've had a few visitors come in and have a look.''
According to the Royal Astronomical Society of New Zealand website, Venus is visible as a small black dot on the face of the sun.
It is very small _ only 3 per cent of the diameter of the sun, and appears as an intensely black spot in contrast to the bright sun.
People were warned that staring directly at the sun could cause serious eye damage.
The Royal Australian and New Zealand College of Ophthalmologists encouraged people to watch the event online or on television.
"No matter what recommended technique you use, do not stare continuously at the Sun and do not use sunglasses alone as they don't offer your eyes sufficient protection.
"There are no pain receptors on the retina so you won't even know you are doing damage.''
It is the same occurrence that Captain James Cook was dispatched to Tahiti on HMS Endeavour to observe in Tahiti June 3, 1769.
VIEWING THE TRANSIT WORLDWIDE
The rare event was being viewed around the world today.
"If you can see the mole on Cindy Crawford's face, you can see Venus," Van Webster, a member of the Los Angeles Astronomical Society, told anyone who stopped by his telescope for a peek on Mount Hollywood.
For astronomers, the transit wasn't just a rare planetary spectacle. It was also one of those events they hoped would spark curiosity about the universe and our place in it.
Sul Ah Chim, a researcher at the Korea Astronomy and Space Science Institute in South Korea, said he hoped people see life from a larger perspective, and "not get caught up in their small, everyday problems."
"When you think about it from the context of the universe, 105 years is a very short period of time and the Earth is only a small, pale blue spot," he said.
While astronomers used the latest technology to document the transit, American astronaut Don Pettit aboard the International Space Station was planning to take photos of the event and post them online.
Meanwhile, terrestrial stargazers were warned to only look at the celestial event with a properly filtered telescope or cardboard eclipse glasses. If the sun is viewed directly, permanent eye damage could result.
In Los Angeles, throngs jammed Mount Hollywood where the Griffith Observatory rolled out the red carpet for Venus. The last time the city witnessed a Venus transit was 130 years ago in 1882. A 2004 transit was not visible from the western U.S.
Telescopes with special filters were set up next to the lawn and people took turns peering at the sun before and during the transit. Astronomers and volunteers lectured about the rarity of a Venus pass to anyone who would listen.
Minutes before Venus first touched the outer edge of the sun, Sousa's "Transit Of Venus March" blared through. The crowd turned their attention skyward. For nearly 18 minutes, Venus appeared as a black spot.
Jamie Jetton took the day off from work to bring her two nephews, 6 and 11, visiting from Arizona to the observatory. Sporting eclipse glasses, it took a little while before they spotted Venus.
"I'm still having fun. It's an experience. It's something we'll talk about for the rest of our lives," she said.
In Mexico, at least 100 people lined up two hours early to view the event through telescopes or one of the 150 special viewing glasses on hand, officials said. Observation points were also set up at a dozen locations.
Venus, which is extremely hot, is one of Earth's two neighbors and is so close in size to our planet that scientists at times call them near-twins. During the transit, it will appear as a small dot.
This will be the seventh transit visible since German astronomer Johannes Kepler first predicted the phenomenon in the 17th century. Because of the shape and speed of Venus' orbit around the sun and its relationship to Earth's annual trip, transits occur in pairs separated by more than a century.
It's nowhere near as dramatic and awe-inspiring as a total solar eclipse, which sweeps a shadow across the Earth, but there will be six more of those this decade.
In Hawaii, astronomers planned viewings at Waikiki Beach, Pearl Harbor and Ko Olina. At Waikiki, officials planned to show webcasts as seen from telescopes from volcanoes Mauna Kea on the Big Island and Haleakala on Maui.
Nasa planned a watch party at its Goddard Visitor Center in Maryland with solar telescopes, "Hubble-quality" images from its Solar Dynamics Observatory Mission and expert commentary and presentations.
Most people don't tend to gaze at the sun for long periods of time because it's painful and people instinctively look away. But there's the temptation to stare at it during sky shows like solar eclipses or transits of Venus.
The eye has a lens and if you stare at the sun, it concentrates sunlight on the retina and can burn a hole through it. It's similar to when you hold a magnifying glass under the blazing sun and light a piece of paper on fire.
It can take several hours for people to notice problems with their eyes but, by that time, the damage is done and, in some cases, irreversible.
During the 1970 solar eclipse visible from the eastern U.S., 145 burns of the retina were reported, according to the American Academy of Ophthalmology.
Experts from Hong Kong's Space Museum and local astronomical groups were organizing a viewing Wednesday outside the museum's building on the Kowloon waterfront overlooking the southern Chinese city's famed Victoria Harbor.
The transit is happening during a 6-hour, 40-minute span that began just after 2200 GMT. What you can see and for how long depends on what the sun's doing in your region during that exact window, and the weather.
Those in most areas of North and Central America will see the start of the transit until the sun sets, while those in western Asia, the eastern half of Africa and most of Europe will catch the transit's end once the sun comes up.
Hawaii, Alaska, eastern Australia and eastern Asia including Japan, North and South Korea and eastern China will get the whole show since the entire transit will happen during daylight in those regions.
-AP, Otago Daily Times, APNZ and Herald Online
