Looking at the photos of astronomical observatories, we can see that many observatories are built on the tops of high mountains. Is this to be closer to the stars? Of course not. There are several main considerations. Firstly, it's to avoid low-altitude clouds and haze. Generally, the height of fog is several hundred meters, and low clouds are distributed below an altitude of 2,000 meters, while medium clouds are distributed around 4,000 meters. If a mountain is above an altitude of 4,000 meters, it can avoid many clouds obscuring the stars. Secondly, the atmosphere on high mountains is relatively quiet, allowing for clearer images of celestial objects. Thirdly, the water vapor density is high in low-altitude areas, which absorbs infrared and some radio waves severely. However, on high mountains, the water vapor density is low, allowing for observations in more wavebands. Dry deserts, which are also home to some telescopes, also meet this condition.
Are there better astronomical observatory sites on Earth than high mountains and deserts? Antarctica is such a place. The ice-covered Antarctic continent is a plateau. At Ice Dome A near the South Pole, the altitude exceeds 4,000 meters, and it's also an extremely dry place with even less water vapor in the air than deserts, making it one of the best observation sites on Earth. In addition, Antarctica has the phenomena of polar day and polar night, allowing astronomers to continuously observe the stars for several months in the dark. China is building the South Pole Survey Telescope at Ice Dome A to study cutting-edge astronomical topics such as black holes, dark matter, dark energy, and the origin of the universe.