Rare event recalled by loose change

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French franc, 1866. Collection of Southland Museum and Art Gallery. Gift of the Department of Conservation, Southland Conservancy, 2006. 2007.472

IF this year has taught us anything, it is that things don’t always go to plan.

But as this French franc reminds us, failed ventures can also generate positive outcomes.
Minted in France in 1866, this coin was found on Moutere Ihupuku/Campbell Island in 1976.

The coin was likely discarded or lost during a French expedition to the island in 1874.

The purpose of this visit was to observe a rare astronomical phenomenon known as the transit of Venus.

During a transit, the planet Venus becomes visible as a small black dot moving across the face of the sun.

This phenomenon is witnessed twice every 243 years, with an eight year gap between each pair.

The 1874 transit was of great interest to scientists at the time because it offered them the
opportunity to calculate the average distance from the Earth to the sun (a measurement now known as the Astronomical Unit).

Scientific institutions in Europe and America therefore began dispatching teams to strategic
locations around the globe to set up observational sites, including locations in Aotearoa New Zealand.

One of the sites selected by the French Academy of Sciences was Moutere Ihupuku.
The task of preparing Moutere Ihupuku for the transit began in late 1873.

The crew of the naval frigate Vire spent a month on the island surveying the coastline and
preparing pathways through the scrub.

The team which would observe the transit arrived in September 1874 and spent several months building a camp and a stone jetty, and setting up their equipment.

On December 9, the day of the transit finally rolled around. Sadly the weather was not on their side.

At the start of the day the sun shone fitfully, but as noon approached the sun became
obscured by clouds and thick mist.

The sun remained out of sight for the rest of the day, but for a handful of seconds when the telescope operator got a tantalising glimpse of the big event.

The disappointed crew spent the following few weeks packing up the camp before setting sail home. But while inclement weather saw the party leave the island without any measurements to contribute to the global scientific project that surrounded the transit, the mission resulted in outcomes of a different kind.

The survey carried out by the crew of the Vire subsequently formed the basis of maps of the island for several decades, and one of the scientists sent to observe the transit, Henri Filhol, went on to publish an account of the natural history of the island.

New Zealand’s role in the transits also acted as a catalyst for the rapid growth of local interest in astronomy, which later lead to the formation of organisations such as the Southland Astronomical Society that is still active today.

— Kimberley Stephenson is the collections manager at Southland Museum & Art Gallery Niho o te Taniwha

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