You will now listen to part of a lecture. You will then be asked a question abo

I’d like to say a few words about how a site is chosen for an observatory. True, the question doesn’t seem exciting, but in fact its answer has a lot of importance for our research as astronomers. Really, there are only two main factors to take into account.
The first factor has to do with humidity. Is the air dry? Wet air is not good for an observatory because the tiny water droplets in the air tend to make what we see through the telescope a blur.
Plus, these water droplets can carry dust, making the image seen even more blurry. For this reason, most observatories are located in the desert, preferably at a high elevation. The air there is dry and the higher you go the less water the air carries. Right now, there is an observatory being built at Atacama in Chile’s desert. The site is nearly 5,000 meters above the sea level. So the view should be wonderful.
The second factor has to do with light pollution. Is anyone here from a farm? Did you ever notice how, in the city, you can see so very few stars? But in the country, the sky just blooms with stars! The reason is the bright lights of the big city interferes with a huge telescope even more than it does with our human eyes. After all, telescopes gather light and make it more intense. So an observatory must be located well away from the cities.