Current DateSeptember 19, 2021

The best place one earth to watch stars

Researchers have just identified the best place on Earth to observe the stars through a telescope. But before you start packing your bags… there are a few things you should know: this place in Antarctica is one of the coldest and most remote on the planet.

For most of us, star-gazing involves moving as far as possible from any source of light pollution, which is usually the case in big cities or areas of high human concentration. This is ultimately the one and only factor to take into account. However, when you are an astronomer and need to look “deep” into the night sky, another factor must be taken into account: the atmosphere.

For this reason, many observatories have been built at high altitudes, at mid-latitudes and where the humidity is very low. This is particularly the case in Chile or Hawaii for example. But could we do better? It seems so!

Antarctica does indeed offer even better conditions, according to a recent study published in Nature. The researchers specifically refer to Dome A, an ice shelf found 1,200 km inland on the eastern side of the continent.

“A telescope located there could surpass a similar telescope located at any other astronomical site,” said Paul Hickson, co-author of the study. “The combination of high altitude, low temperatures, long periods of continuous darkness and an exceptionally stable atmosphere makes Dome A a very attractive location for optical and infrared astronomy. A telescope located there would have sharper images and could detect dimmer objects ”.

One of the greatest challenges in Earth-based astronomy is to overcome the effect of atmospheric turbulence on the image quality of the telescope. This turbulence indeed makes the stars twinkle. Thus, the less there is, the clearer the images.

These turbulences take place in the so-called “boundary” layer of the atmosphere. In other words, they happen in the lowest layer. That which is influenced by the friction of the surface of the Earth. However, the big advantage of Dome A is that it is located at an altitude of over 4000 meters, under a thinner “boundary layer”. It thus allows better access to the so-called “free” atmosphere where turbulence is less felt.

Astronomers measure this atmospheric turbulence in arc seconds. The lower the number, the better.

Some of the best astronomical sites in the world, such as the observatories in Chile and Hawaii, display numbers between 0.6 and 0.8 arc seconds. However, according to this new study, which is based on an observation of the sky for seven months at eight meters high, Dome A would have a night vision capacity of only 0.13 arc second.

Note that the low temperatures are in themselves the main obstacle to the experiment. And for good reason, Dome A is located in one of the coldest places on the planet. However, by finding ways to get around this problem, the researchers say that vision could be improved by an additional 10 to 12%.

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