Today is D-Day – the transit of Venus will be visible from New Zealand for the first time in 130 years. If you get the chance then I urge you to get out and take a look as you won’t live to have another opportunity. Just make sure that you don’t look directly at the sun (especially through binoculars or a telescope) without the proper protection. Visit this site for a good write-up on techniques you can use to watch the transit or go along to your local observatory. If the weather packs in then try watching it live online courtesy of NASA.
The transit of Venus has special historical significance to New Zealanders. In 1769 the Royal Society sent none other than Captain Cook to the South Pacific to observe the transit of Venus. But why go to all that effort to send him to such a distant part of the globe?
It has everything to do with parallax – a word that thanks to the surge in 3D films is well-known to anyone in the cinema industry. In simple terms, if you look at an object from two slightly different viewpoints you can use the difference between them to perceive depth. This is how the human eyes work. Now imagine that on a celestial scale. If you view the transit from different parts of the globe then it is possible to calculate the solar parallax and from that calculate the distance between the Earth and the Sun.
Since Captain Cook’s first visit in 1769 two more transits of Venus have been visible from New Zealand – one in 1874 and the other in 1882. Both of these attracted the interest of local astronomers and scientific expeditions from the northern hemisphere. They wanted to refine the calculations of the previous century and to help with that task they brought with them something that Captain Cook didn’t have – cameras.
You have to wonder if these intrepid astronomers were the gambling types or simply didn’t know about New Zealand’s often-unpredictable climate. Perhaps someone should’ve mentioned to them that the native Māori name for New Zealand is ‘Aotearoa’ – meaning “The land of the long white cloud”. Although back then ‘Aotearoa’ was only used to refer to the North Island and not the South. Perhaps that is why some of the teams favoured Canterbury and Otago.
I can only imagine how nervous they must have been during the build up to the big day, having traveled across the world with all that equipment for the sole purpose of observing the transit. How they must have scanned the skies the night before, praying, hoping for good weather. Here in 2012 I can sympathize a little with them. Currently there are storms and snow forecast and no guarantee that they will clear in time for the once in a lifetime chance to view the transit of Venus. So how did those early astronomers fair during the last two transits that were visible from New Zealand? Was their view unimpeded or did the weather spoil their view?
1874 TRANSIT OF VENUS
A number of international scientific teams visited New Zealand and its outlying islands to observe the transit of ’74. But which teams picked the right spot to view a complete cloud-free transit? Here are the results:
The French team
Location: Campbell Island
Prediction: Storms damaged their camp and the day itself looked to be cloudy.
Outcome: Only got a few short glimpses of the transit.
The German team
Location: Auckland Islands
Outcome: The rain cleared just in time and they successfully observed most of the transit. On a silly side note, I can’t help but wonder how the French and Germans decided on who would take what island (as I can’t imagine them sharing one!). I like to think that a duel was involved but when it came to scientific advancement relationships were usually pretty civil, even between warring nations.
The British team
Location: Burnham, outside of Christchurch
Prediction: “The weather is fine with every prospect of being favourable for observing the transit of Venus”
Outcome: The official report reveals that it was mostly unsuccessful due to poor weather, but it did clear enough for the team to briefly view the transit and take some photographs, one of which can be seen here.
The First American team
Location: Chatham Islands
Prediction: Unknown – but they had terrible luck. The chief photographer died of yellow fever on the way there and they were plagued by technical problems.
Outcome: Thin cloud followed by rain.
The Second American team
Prediction: “Weather looks threatening; heavy banks of clouds have been visible all day. Fears are entertained for the success of the Transit of Venus observation. Great anxiety felt.”
Outcome: The following telegram was received from the telegraphist at Queenstown: “Pleased to inform you that Professor Peters, the American astronomer, was very successful in taking observations of the transit of Venus here”. The American team took several hundred photographs of the transit but none are known to have survived. This was by far the most successful of the 1874 observations made from New Zealand. A plaque commemorates the site of the American camp, now occupied by the Millennium Hotel.
1882 TRANSIT OF VENUS
The transit of ’82 offered teams a second chance. There was less international interest in New Zealand but two expeditions did make the trip.
The American Team
Location: The Domain, Auckland
Outcome: A success! They took at least 75 photographs. This must have been particularly satisfying for the expedition leader, Edwin Smith, who’s previous expedition to the Chatham Islands was unsuccessful.
The British Team
Location: Burnham, Christchurch (Same location as the mostly unsuccessful 1874 observation)
Outcome: “For some little time after sunrise this morning light cirrus clouds proved an obstacle to a clear definition of the transit of Venus, but during later stages the atmosphere was perfectly clear. Immense numbers of people were watching the phenomenon. The operations by the English observers at Burnham were highly successful.”
Astronomical timescales are never friendly to ephemeral beings such as us. With only one or two chances in any human lifetime to view the transit you can feel sympathetic towards those who dedicated so much time and money only to have their one chance spoiled by poor weather. In New Zealand there was one scientist who appears to be the unluckiest – James Hector.
During the 1874 transit Dr. Hector based himself at the Colonial Time Service Observatory in the Botanic Garden in Wellington. Unfortunately dark clouds obscured the view of the transit. In 1882 he went to the South Island, perhaps with the thought of replicating the success of the previous American expedition.
The Evening Post gleefully regaled its readers with a description of the transit.
“A superb morning broke on this eventful date of the long-looked-for transit of Venus…. The dark body of the planet could plainly be seen even with the naked eye, protected by smoked glass, as the sun rose, and it remained uninterruptedly visible to the end…. It is our pleasing duty to record an almost unqualified success for the New Zealand observations”
The poor unfortunate ‘almost’ that the Evening Post referred to was Dr. Hector who had based himself in Clyde. Dense cloud had obscured his view just as Venus made its first point of contact. However fortunately it did later clear enough for him to get at least a brief view of the transit, during which he was able to see Venus atmosphere.
Here in the 21st century keen astronomers are just as much at the mercy of the weather as their predecessors. There is still scientific merit in the observations of the transit of Venus. One exciting area of research is using the transit to help focus efforts to locate exoplanets – so I’m only exaggerating a little when I say that the 2012 transit of Venus is aiding our search for aliens! But for most of us the transit is a curiosity, a reminder of how short our lifespan Is on the celestial calendar, a reminder of how short our shared modern history is and a once in a lifetime chance to share a short moment with those explorers and scientists from the history books; to look skyward to see another world silhouetted against the sun – or to raise a fist and curse the water vapor blocking the view.
By the way – it actually is D-Day today. Very appropriate.
© Lemuel Lyes
Here is a semi-relevant New Zealand tune for the day