The Transit of Venus explained
What is the Transit of Venus?
Astronomically speaking, a transit is like an eclipse - where a planet or other celestial body comes between Earth and the Sun - but it does not completely obscure the Sun.
The transition will be visible in New Zealand on June 6 between 10:15am and 4:43pm, provided there is fine weather.
It will appear as a black disc or dot moving slowly across the sun and will only be viewable with safe equipment.
The last transit occurred in 2004 - Venus has an unusual pattern of years between transitions: 8, 105 ½ , 8, 121 ½ and so on.
If you miss this year's transit of Venus, you are unlikely to ever see it again - the next one is expected in 2117 - 105 years from now.
Transits of Venus also have historical significance - a transit in 1769 was the reason Captain James Cook first explored the south Pacific with the aid of Tahitian navigator Tupaia.
How do I watch it?
Never look directly at the sun, especially through a lens like binoculars, a camera or telescope without the correct protective filter - partial or total blindness can result. Children should be supervised.
Carter Observatory will be open on June 6 at half price and will hold viewings of the transit through safe filters. They are also selling solar viewing glasses for $3 per pair.
John Field, Carter Observatory's Programme and Education Officer, recommends you check for objects which may obscure your view of the sun in the spot you want to watch from.
"Here in Wellington the Transit commences at 10:15 am and the best vantage points would from the western hills in the Hutt Valley, looking towards the northeast," he said.
"For Porirua, the best viewing would be from the western hills. From Wellington City Mount Victoria, Brooklyn would be good locations.
"The transit ends at 4:45 pm and by this time the Sun will be low in the west. Viewing from the west coast, Makara, Plimmerton, Paraparaumu Beach will be the best locations.
"In the Hutt Valley the higher on the eastern hills the better and in Wellington Wrights Hill would be good."
If the weather doesn't allow for viewing, there are live streams of the transit available online at www.slooh.com, http://venustransit.nasa.gov/transitofvenus/ and http://www.space.com/14568-venus-transits-sun-2012-skywatching.html
Make your own solar viewer
One method of viewing the sun safely involves using binoculars to project an image of the sun on to a flat object.
Keep one of the lenses capped and face the larger end towards the sun to allow the light to pass through and project on to a large white object - a wall or similar.
You should see a bright disc. Adjust the distance between the binoculars and the wall to get the disc about the size of a medium plate. If it is blurry, use the focus on your binoculars to make it sharp.
- © Fairfax NZ News