Excuse me: The famous observatories in the world and China.

The observatory is mainly an astronomical observation and research institution, and most of the observatories in the world are located in mountainous areas.

Most of the observatories in China are also located in mountainous areas. For example, the Purple Mountain Observatory is located on the Purple Mountain in the northeast outside Nanjing, with an altitude of 267 meters. There are five observatories in Beijing Observatory, of which Xinglong Observatory is about 940m above sea level and Miyun Observatory is about150m above sea level. The workstation of Shanghai Observatory in Sheshan is also 98 meters above sea level. Yunnan Observatory is located in the eastern suburb of Kunming, with an altitude of 2020 meters.

The main job of the Observatory is to observe the stars with astronomical telescopes. Is the observatory located on the mountain because the mountain is closer to the stars?

That's not true.

The stars are far away from us. Generally, stars are hundreds of trillion kilometers away from us, and the nearest celestial body, the moon, is 380 thousand kilometers away from the earth. The mountains on the earth are generally only a few kilometers long, so it is obviously insignificant to shorten such a short distance.

The earth is surrounded by the atmosphere, and starlight has to pass through the atmosphere to reach the astronomical telescope. Smoke, dust and water vapor fluctuations in starch gas all have effects on astronomical observation. Especially near big cities, city lights illuminate these particles in the air at night, which makes the sky bright and makes it impossible for astronomers to observe darker stars. Far away from the city, there is less dust and smoke, and the situation is better, but these effects are inevitable.

The higher the place, the thinner the air, the less smoke and water vapor, and the smaller the impact, so most observatories are located in the mountains.

At present, the three best observation sites recognized in the world are located at the top of the mountain, which is the top of Mauna Kea Mountain in Hawaii, with an altitude of 4,206 meters. Chilean Andes, 2500 meters above sea level; And the Canary Islands in the Atlantic Ocean, with the highest peak of 2,426 meters.

The roof of an ordinary house is either flat or inclined, but the roof of the Observatory is different. Seen from a distance, the silver-white round roof is like a big steamed bun, shining in the sun.

Why did the Observatory build a dome structure? Is it to look good? No, the dome of the observatory is not for beauty at all, but has its special purpose. The houses with silver domes we see are actually observation rooms of the Observatory, and their roofs are hemispherical.

On closer inspection, there is a wide crack on the hemisphere, from the roof to the place where the house is located. After entering the house, you see, hey! Where is the crack? It turned out to be a huge skylight through which a huge astronomical telescope pointed to the vast space.

The observation room of the Observatory is designed in a semicircle to facilitate observation. At the observatory, people observe space through astronomical telescopes, which are often too big to move around. The targets observed by astronomical telescopes are distributed in all directions of the sky. If you use an ordinary roof, it is difficult to point the telescope in any direction at will. The roof of the observatory is spherical, and a mechanical rotating system controlled by computer is installed at the joint between the dome and the wall, which makes observation and research very convenient. In this way, when observing with an astronomical telescope, you only need to turn the circular roof to turn the skylight to the direction to be observed, and the telescope will also turn in the same direction, and then adjust the lens of the astronomical telescope up and down to point the telescope at any target in the sky.

When not in use, the telescope can be protected from wind and rain by closing the skylight on the dome.

Of course, not all observation rooms in the observatory have to be made into circular roofs. Some astronomical observations can be made into rectangular or square rooms as long as they are aimed at the north. There is a long skylight in the center of the roof, and the astronomical telescope can work.