New Zealand is in a prime spot for viewing this symbolic event in our history.
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On June 6 next year, the planet Venus will pass between the Earth and the Sun. This rare planetary alignment – called the transit of Venus – happens in pairs eight years apart, with each pair separated by more than 100 years. New Zealand was one of the few countries to miss the 2004 transit – by the time Venus began its path across the Sun it had already set in our part of the world – but in 2012 all New Zealanders will have an opportunity to observe this rare phenomenon.
The transit of Venus is the subject of a beautiful new book by Australian astronomer Nick Lomb. As told by Lomb, the first observation of a transit of Venus was in 1639 – just 30 years after Galileo first pointed a telescope at the skies. For the event, predicted by the European astronomer Johannes Kepler, an Englishman named Jeremiah Horrocks projected an image of the sun on the wall of a darkened room and observed the progression of the small black dot across the circle of the sun.
More than 100 years later, Edmund Halley – of the itinerant comet – published details of how observation of the exact times of a transit of Venus from different known points on Earth, combined with some simple geometry, could allow the calculation of the distance from the Earth to the Sun, and from there, the size of the entire solar system. This, Lomb says, “was to capture the imagination of astronomers”.
Observation of the next pair of transits, in 1761 and 1769, became the first global scientific collaboration. In 1761, European astronomers observed the transit of Venus from Africa, Siberia and Norway as well as from the islands of St Helena, Sumatra and Mauritius, but the resulting calculations for the distance from the Earth to the Sun were so varied that the observations were declared a failure. A successful calculation now hinged on observations of the 1769 transit and London’s Royal Society sent James Cook to Tahiti. Here, Cook set up a fort – Fort Venus – to protect his men and their equipment.
Despite their fortifications a local man managed to run off with the quadrant, an instrument vital for determining the geographical location of their observation site. The quadrant was retrieved, though, and Cook, astronomer Charles Green and botanist Joseph Banks all observed the transit on June 3, 1769, carefully recording the time of contact of the shadow of Venus against the sun. After observing the transit, Cook opened a set of sealed instructions from the Royal Society that directed him to sail south in search of Terra Australis Incognita, the unknown southern continent. If he was unsuccessful, he was to chart the islands of New Zealand then sail home.
New Zealand doesn’t get more than a mention in Lomb’s book, but it is going to be one of the best places in the world to observe the 2012 transit. The focus of New Zealand’s celebration of the event will be at Tolaga Bay (known to its original inhabitants as Uawa), where the local community, including Te Aitanga-a-Hauiti, will host professional and amateur astronomers, a visiting Royal New Zealand Navy ship and delegates of a conference – Lifting our Horizons – being held at Gisborne immediately after the transit.
“It’s an extremely symbolic event in the history of our country,” says conference leader Professor Sir Paul Callaghan, who describes Cook’s landfall at Uawa, where his men came ashore and communicated and traded with local Maori, as “the beginning of the dual heritage between Maori and European in New Zealand’s history”. And just as science played a role in that first contact, says Callaghan, it can play a key role in New Zealand’s future. As a consequence, a focus of the conference will be how scientists and a science-based economy can make a difference to New Zealand’s future – in regions like the East Coast as well as in the big cities.
The conference is restricted to registered guests, but anyone can watch the transit, from almost anywhere in New Zealand. Venus will take its journey across the sun from about 10am to 5pm, depending on where in New Zealand you are, but – as with a solar eclipse – care must be taken when observing. Eye specialist Ralph Chou recommends watching it through a welder’s glass, or – a great way to watch as a group – by projecting an image of the sun, with binoculars or a telescope – onto a white wall. Observatories around the country will host public viewings, and for people who prefer to see the transit through other people’s eyes, Victoria University’s Adam Art Gallery will host an exhibition, Dark Sky, that includes early images of the transit of Venus.
Next year’s transit of Venus won’t be of particular scientific value – the 2004 transit was observed from space, the average distance from the Earth to the Sun has now been accurately calculated as 149.6 million kilometres and the surface of Venus has been photographed and mapped by Nasa’s Magellan mission – but the event has enormous historical and cultural significance.
The 2012 transit of Venus is likely to be the last one anyone alive today has the chance to see – the next one won’t be until 2117. As British astronomer William Harkness wondered, after observing the 1874 transit from Hobart, Australia, what will the world be like when the next transit takes place? And what role will science play in that future?
TRANSIT OF VENUS: 1631 TO THE PRESENT, by Nick Lomb (New South Publishing, $60).
QUESTIONS, ANYONE?
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What is the Higgs boson? How do cicadas make that annoying sound? Why do batteries drain faster in cold weather? Do you have a pressing science question that needs an answer? Send your questions to science@listener.co.nz and I’ll answer them – or find someone who can – in an upcoming column.
MOLECULE OF THE YEAR
An online competition to determine the molecule that has most changed New Zealand society has a winner. Carbon, that ubiquitous, yet atmospherically troublesome building block of life – “It’s in the soil, and every tree/And my dad says it makes me, me” – was nominated, in verse, by Spike O’Conner and his dad, Frank, and got the most online votes. Second place went to caffeine, “an alkaloid synthesised from purine nucleotide precursors by a number of plant species”, according to biochemist Wayne Patrick, who rightly asked “where would we be without it?” Third place was shared by keratin, a fibrous protein found in wool, and 1080, the possum-killing poison. The Molecular Anthology competition was organised by the Manawatu Branch of the New Zealand Institute of Chemistry for the 2011 International Year of Chemistry.
TOILET PAPER SCORECARD
It started with the Greenpeace Red Fish List (don’t buy!) and the Good Wood Guide (do buy!). Then Friends of the Earth published a Safe Sunscreen Guide for consumers who want to avoid nanoparticles. Now consumers can choose a “wildlife friendly toilet roll”. Forensic testing and on-the-ground research by Greenpeace has showed that Cottonsoft toilet paper contains fibres from Indonesian rainforests. Two other brands – Paseo and Kiwisoft – have failed to prove their paper comes from rainforest-friendly sources. Don’t buy! Instead, look at the Greenpeace or WWF websites for a list of nine toilet paper brands made from either recycled paper or with the Forest Stewardship Council stamp of approval.