The search for the best observatory site in the world has lead to the discovery of 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 three times sharper than any ever taken from the ground.

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 70ºC 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 and visiting professor to UNSW, 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 finding is published today in the Publications of the Astronomical Society. Located within the Australian Antarctic Territory, the site is 144km from an international robotic observatory and the proposed new Chinese 'Kunlun' base at Dome A.

Interest in Antarctica as a site for astronomical and space observatories has accelerated since 2004 when UNSW astronomers published a paper in the journal Nature 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 high, flat, and cold environment of the Antarctic Plateau at Dome C, one of the areas that astronomers have identified recently as a possible location for a future observatory. (Credit: Stephen Hudson / Courtesy of Wikimedia Commons)"

Source: University of New South Wales