The Last Transit of Venus for 105 years

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*** FOR IMMEDIATE RELEASE ***
Released: Thursday 31st May 2012

The Last Transit of Venus for 105 years - from Horowhenua to the World

The Horowhenua Astronomical Society Inc (HASI) is very pleased to announce that they will be webcasting live coverage of the Transit of Venus on Wednesday 6th of June. The entire webcast will be playing live at the Levin Library on a large projector screen, and available for viewing around the world via the HASI website as well as UStream TV. Coverage will be from 10am until 5pm.

Transits occur when a planet with a smaller orbit than us passes between the Earth and the Sun, and in the same orbital plane, so there are only 2 planets in our solar system that we can see transiting across the face of the Sun - Venus and Mercury. HASI President, Dr Stephen Chadwick, said "Transits of Venus are a surprisingly rare occurrence because, although Venus passes between the Earth and the Sun every 1.6 years, the orbit of Venus is inclined to the orbit of Earth. Therefore, Venus is usually above or below the Sun as viewed from Earth."

Mike White, Events Coordinator said "Transits of Venus occur in pairs, 8 years apart, followed by a gap of either 105.5 or 121.5 years before the pattern repeats. The last transit occurred in 2004, so this is the second transit of the pair - the next will not occur until 2117, and I doubt many of us living today will still be around to see that!".

"Not only is the Transit of Venus an extremely rare event (only 7 have occurred since the invention of the telescope 400 years ago), but it is also of great historical significance to New Zealand and the South Pacific" says Mike. "It was the 1769 transit that brought Captain Cook to Tahiti. He then continued south to map the coast of New Zealand and observe a transit of Mercury".

The astronomical and scientific aspect of transits are important too - it was the measurement and accurate timing of these historical events that enabled astronomers to calculate the distance between Earth and the Sun, using trigonometric formulae, and subsequently to estimate the size of our solar system. The principle of parallax was used to calculate distance in these transit observations. If the transit is viewed from two different locations simultaneously, but widely separated by distance, the transiting planet will appear to be in a different point in relation to the background Sun. The angle between these two points can be used to calculate distance.

"You can see the effect of parallax for yourself" says Stephen Chadwick, "simply by holding up a finger at arms length and closing one eye, and then the other. Your finger will appear to move in relation to the background. The principle is the same for planets, but on a much grander scale, so simultaneous observations must be done from locations that are widely separated geographically. In fact, that is also part of our mission for this particular transit event. Aside from wanting to provide free coverage to the public, the Horowhenua Astronomical Society is also joining forces with the Stockton Astronomical Society in California to provide simultaneous images of the transit to US university students to calculate the Earth-Sun distance for themselves".

As exciting as it is to witness an astronomical event of such rarity, we have a word of caution - NEVER look at the sun with the naked eye (even sunglasses are nowhere near sufficient!), and NEVER look at the sun through binoculars or telescope without proper solar filters! The much safer option is to join us online or at the Levin Library to be a part of history. The webcast can be viewed at:-
www.horoastronomy.org.nz/stargazing/broadcast
or www.ustream.tv/channel/astro-mike

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