The Skies Above

Many things have brought people to the Chatham Islands; escape, adventure, sanctuary, and fortune have all played their part, but 150 years ago something very different drew the U.S. navy ship Swatara to the Chathams.

Millions Of Kilometres Away a planet nearly as small as ours was about to slide across the massive face of our sun, in a rare astronomical occurrence known as the Transit of Venus. First observed in 1639, there had been only two further transits prior to the Swatara’s arrival in October 1874, and for those onboard that year’s Transit was not to be missed for the world.

USS Swatara at the New York Navy Yard

For astronomers, the importance of the Transit is hard to overstate. The planet’s travels through our skies have been watched for hundreds of years; but it is only when it transits precisely across the sun in a rare alignment that it can be used to help us to refine the astronomical unit, a measurement used primarily for measuring distances within the solar system or around other stars.

So important is this unit that scientists travelled huge distances in the hopes of clear skies to observe the Transit and further our understanding of where we are in the grand scheme of things; in 1769, James Cook had sailed to Tahiti to see one (and this ultimately led to his visits to Aotearoa), while other scientists went to California and Norway.

The team that weighed anchor in 1874 in the Chatham’s Whangaroa Harbour (Port Hutt) was the first bilateral science collaboration between the United States and New Zealand. It was also part of a much wider collaborative effort involving seven nations and their colonies observing the Transit around the globe. In New Zealand, the French watched from the Campbell Islands, the Germans from the Auckland Islands and another American expedition set up camp in Queenstown.

A still image of Venus passing the face of the Sun.

It was a remarkable piece of scientific cooperation, all organised in the days before reaching out to the other side of the world involved a lot more time and effort than just pressing send on an email!

The Swatara was ultra-modern - she had only been launched the previous year - and was captained by Commander Ralph Chandler of the U.S. Navy. The nine-strong observation team was led by chief astronomer Edwin Smith, and included a 19-year-old photographer named William H Rau, as this was to be the first time photography was employed in a Transit observation. A ‘kiosk’ was constructed for the observation and the various pieces of technical apparatus set up in readiness for the big day, and a big day it was to be, as a type of Transit feeder was gripping the country! The booklet The Transit of Venus and How to Observe It had been penned by Arthur Stock of the Colonial Observatory in Wellington and Kiwi skywatchers were getting in on the action.

Aboard the Swatara, Rau had photographed some of the world’s most remote places but was far less successful in capturing the Transit itself; first his tent caught fire, and then cloudy skies and his primitive equipment meant that none of Rau’s photographs were sharp enough to be of true scientific use. (Rau had much better luck back home in the U.S., where he went on to become a very successful and widely recognised photographer.)

Those observing with the human eye had more success, and the expedition meant New Zealand was able to make quite a dramatic entry into international astronomy. But perhaps the best outcome from Whangaroa Harbour all those years ago was the cooperation between the United States and New Zealand, a partnership that has led to a long and still fruitful working relationship that endures to this day.

Above is Transit house and instruments, used on the Chatham Islands during the United States expedition to observe the transit of Venus in 1874. Photograph taken by William H Rau.