Aurora and stars, seen from Amundsen-Scott South Pole station in July 2020
Geoff Chen
If you want to get the best possible view of the stars from here on Earth, you should prepare for a long journey to the coldest place on the planet. About 650 miles inland from the eastern tip of Antarctica, you will find yourself on an immaculate, white plateau stretching to the horizon: Dome A.
A new study by Chinese researchers at the research station located in Dome A, published in the journal Nature on Wednesday, suggests that it might be the best place on Earth for astronomers to examine the skies. But first you have to get there.
The walk to Dome A is intense.
First, you must get to Antarctica. It’s not that difficult these days, but you should take an icebreaker so you can drop it off the eastern Antarctic coast. A helicopter takes you from the ship to the frozen continent, and then the real journey begins. From there, you drive through the ice in a shipping container-like vehicle, hauled by a tractor at about 10 kilometers (6 miles) per hour. It takes approximately two weeks to reach your destination.
Only then can you start installing your telescope on an eight-meter-high platform in the middle of the ice desert.
That is exactly what the team of researchers did during the summer of 2018-19, and they report that the weather conditions are so good that their views of the night sky are different than anywhere else on Earth.
“The experience was unique and exciting,” says Zhaohui Shang, one of the researchers who was part of the expedition and co-author of the study. “We had a very intense job to complete, with only about 3 weeks in the summer at Dome A.”
The location of Dome A.
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Immaculate heaven
Dome A has long been considered a great place to stargaze. But what makes the coldest place on Earth particularly good for viewing the cosmos?
“It all comes down to atmospheric turbulence,” explains Michael Ashley, an astrophysicist at the University of New South Wales and co-author of the study.
“If you go to a good dark place somewhere, you see the stars blink and the blink is bad.”
The twinkle, Ashley says, is caused by Earth’s atmosphere and is not helpful to astronomers trying to imagine the cosmos. But in Antarctica, there is very little turbulence, because it is very flat and the winds moving through the area are extremely light.
“If you only have winds blowing on a completely flat snow surface, there is no opportunity to generate turbulence,” he explains.
Ice to see you: the telescope installed in Dome A.
Furthermore, water vapor can wreak havoc in astronomy because it absorbs light, particularly at infrared wavelengths. But Antarctica is very dry, the water freezes, and that is a great advantage for those looking to study the sky. Particularly if you want to study the cosmos in the millimeter wavelength, as the Atacama matrix does in the Chilean desert.
“We took a terahertz telescope and got spectacular data,” says Ashley.
“And we are much better than Atacama in terms of site conditions.”
The telescope observations at Dome A are approximately two and a half times better than those seen at some of the best ground-based observatories in Chile or Hawaii.
China plans to build another infrared optical telescope at the site known as the Kunlun Dark Universe Survey Telescope, KDUST. It has been in process for about a decade and I would see China put a nearly twice as large telescope in place.
“Right now, it’s kind of stuck in a review,” says Ashley. “I think they are looking at it very closely. And I think this Nature article should help a little bit.”
China’s recent scientific efforts also extend far beyond Earth. Last week the country launched the Tianwen-1 mission. A spaceship, which carries three robotic explorers, is way to mars and is expected to arrive there in February 2021.
