Ground-based telescopes are hampered by our planet's atmosphere, which causes light coming from stars to waver. Scientists describe the seeing of a potential telescope site by how much light jittering occurs, which in turn affects the sharpness of the images that can be taken. Michael C. B. Ashley of the University of New South Wales in Australia and his colleagues tested seeing conditions at a site in Antarctica called Dome C, which is located at 75 degrees South Latitude and at an elevation 400 meters higher than the South Pole is. Previous tests at the South Pole had indicated that seeing at the South Pole Station is nearly twice as bad as it is at mid-latitude telescope locations. The researchers determined that conditions at Dome C, however, are two to three times clearer than those experienced at central observatories. This implies a factor of 10 increase in sensitivity, Ashley says. Put another way, an eight-meter telescope on the Antarctic Plateau could achieve the sensitivity limits of a hypothetical 25-meter telescope anywhere else.
Dome C's high elevation, flat surrounding terrain, low wind speeds, and extreme temperatures and humidity contribute to the excellent conditions, the scientists report. The team concludes that Dome C is the best ground-based site to develop a new astronomical observatory and that telescopes positioned there could work on projects that would otherwise require a space mission.