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The optics of ice
My recent holiday to New Zealand gave me the perfect opportunity to see optics in action. Two highlights from my trip were a visit to the Franz Josef glacier to see some amazing blue ice structures and a visit to the Mount John observatory and New Zealand’s largest telescope.
First, lets talk about glaciers and blue ice. Nothing can really prepare you for your first walk on a glacier. Pictures in magazines and television documentaries don’t really do it justice. It is only when you set foot on the glacier and see the sheer scale of the surface structures and their deep colours that you truly appreciate their beauty.
Franz Josef glacier is around 12 km long and our plan was to get in a helicopter and land 3 km up from the glacier’s terminal moraine. Flying over the glacier gave us our first glimpse of just how many cracks and structures are on the surface, and it wasn’t long before we had struck it lucky and were gazing open-mouthed into a deep blue crack in the ice.
Why does the ice appear blue? Here’s the quick answer: In ice, the absorption of light at the red end of the spectrum is greater than at the blue end. A lack of reflected red wavelengths produces the blue colour that the human eye observes.
Two hours and over 200 photographs later (the joy of digital!), we were back in the helicopter and on our way back to the Franz Josef township. What a brilliant experience!
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