What other profession would go to the bottom of the planet to find what is thought to be the coldest, driest, calmest place on Earth. No human is thought to have ever been there but it is expected to yield images of the heavens nearly as good as those from the space-based Hubble telescope -more than three times sharper than any ever taken from the ground.
Guess where?
The joint US-Australian research team combined data from satellites, ground stations and climate models in a study to assess the many factors that affect astronomy – cloud cover, temperature, sky-brightness, water vapor, wind speeds and atmospheric turbulence.
The researchers pinpointed a site, known simply as Ridge A, that is 4,053m high up on the Antarctic Plateau. It is not only particularly remote but extremely cold and dry. The study revealed that Ridge A has an average winter temperature of minus 70°C and that the water content of the entire atmosphere there is sometimes less than the thickness of a human hair.
It is also extremely calm, which means that there is very little of the atmospheric turbulence elsewhere that makes stars appear to twinkle: "It's so calm that there's almost no wind or weather there at all," says Dr Will Saunders, of the Anglo-Australian Observatory, who led the study.
"The astronomical images taken at Ridge A should be at least three times sharper than at the best sites currently used by astronomers," says Dr Saunders. "Because the sky there is so much darker and drier, it means that a modestly-sized telescope there would be as powerful as the largest telescopes anywhere else on earth."
They found that the best place in almost all respects was not the highest point on the Plateau – called Dome A – but 150km away along a flat ridge.
"Ridge A looks to be significantly better than elsewhere on the Antarctic plateau and far superior to the best existing observatories on high mountain tops in Hawaii and Chile," says Dr Saunders. The site is 144km from an international robotic observatory and the proposed new Chinese 'Kunlun' base at Dome A (80.37◦ S 77.53◦ E).
"Australia contains no world-class astronomical sites, and Australian astronomers face a choice between being minor players in telescopes in Chile or joining Chinese or European efforts to build the first major Antarctic observatory," says Dr Saunders.
Go Aussies!
Casey Kazan. Image credit: George Steinmetz, Antarctica Dry Valley
http://www.dailygalaxy.com/my_weblog/2009/09/astronomers-zoom-in-on-coldest-driest-calmest-place-on-earth-guess-where-.html
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