The Clearest Skies on Earth

Telescopes are perched at the tops of mountains because the air up there is thinner, drier and clearer than the view from sea level. But the best views of all are near the south pole in Antarctica, in a region called Dome C. With its high altitude, low temperatures, and crystal clear skies, Dome C boasts nearly perfect viewing conditions. A team of French astronomers are hoping to build a trio of telescopes that work together as a single, large telescope as a prototype. But they’ve got their sights set on a larger installation that could rival the capabilities of the best telescopes on Earth. It’s all about location, location, location.

Concordia station is a research facility located at Dome C, at an altitude of 3,300 metres (10,800 feet) above sea level. During winter nights, temperatures can drop to -63 Celsius (-82 Fahrenheit). This bitter cold removes the thermal background radiation that reduces the sensitivity of telescopes in warmer climes. Furthermore, Dome C enjoys perfectly clear skies 96% of the time.

Although the view from Dome C could never be as good as the view from space, such as with the Hubble Space Telescope, it could be almost as good. Images taken from this spot could be as good as Hubble about 10% of the time, and images in the near-Infrared spectrum could be as good as Hubble 50% of the time.

Sounds like a great place for a telescope.

But the atmosphere at Dome C is perfect for building an interferometer. This is where the light from several telescopes is joined together to act as a single, more powerful telescope. An interferometer built at Dome C could be several times more sensitive than the a similar sized observatory anywhere else on Earth.

In order to test their theories, and prove the quality of the skies at Dome C, French astronomers are proposing to build a prototype interferometer, called Mykerinos, which would consist of three 40cm (16 inch) optical telescopes. The combined light from the three telescopes would give it enough resolving power to detect hot Jupiter-like planets orbiting other stars, or sense high contrasted binaries. And if they could put their telescopes on towers 30 metres (100 feet) high, or use adaptive optics, they could reduce atmospheric distortion even more.

But the team’s true hope is to build an instrument called KEOPS, which would consist of 36 1.5 metre telescopes arranged in 3 concentric rings a kilometre across. The first ring would contain 7 telescopes, the second would have 13, and the third would have 19. This instrument would have the combined surface area of the Keck telescopes, but would be located in Antarctica’s cold, clear skies. With this power and clear skies, it could rival the capabilities of a 30 metre telescope.

Written by Fraser Cain