The coldest, driest, calmest place on Earth

When you’re planning your next holiday, a site known as Ridge A that sits 4,053m (2.5 miles) high up on the Antarctic Plateau, will probably be one of the first places to strike off the list. Although the research team that discovered it says it could be the calmest place on Earth, it is also thought to be the coldest and driest. A joint U.S.-Australian team pinpointed the site by combining data from satellites, ground stations and climate models in an attempt to find the best observatory site in the world by assessing the many factors that affect astronomy, such as cloud cover, temperature, sky-brightness, water vapor, wind speeds and atmospheric turbulence.

Not only is Ridge A particularly remote, it also has an average temperature of -70°C (-94°F) and the entire atmosphere there is sometimes less than the thickness of a human hair. This acute dryness, along with the extreme calm means there is very little of the atmospheric turbulence found elsewhere that makes stars appear to twinkle. This reduced atmospheric interference means that images taken at Ridge A should be a least three times sharper than the best sites currently used by astronomers and that even moderately-sized telescopes there would be as powerful as the largest telescopes anywhere else on Earth.

Interest in Antarctica as a site for astronomical and space observatories has accelerated since 2004 when University of New South Wales astronomers published a paper confirming that a ground-based telescope at Dome C, another Antarctic plateau site, could take images nearly as good as those from the space-based Hubble telescope.

The Ridge A site is located within the Australian Antarctic Territory (81.5◦ S 73.5◦ E) and is 144km from an international robotic observatory and the proposed new Chinese 'Kunlun' base at Dome A (80.37◦ S 77.53◦ E). Last year, the Anglo-Australian Observatory completed the first detailed study into the formidable practical problems of building and running the proposed optical/infra-red PILOT telescope project in Antarctica. The 2.5-meter telescope will cost more than AUD$10million (approx USD$8.4 million at the time of publication) and is planned for construction at the French/Italian Concordia Station at Dome C by 2012.

The findings are food for thought for Australian astronomers, as Australia currently contains no world-class astronomical sites.

“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, of the Anglo-Australian Observatory and visiting professor to UNSW, who led the study.

The research team’s findings appear in the journal Publications of the Astronomical Society.