Our eyes are good enough for simple stargazing.
But they tell us very little about what the stars are really like.
To see the stars more clearly and find out about them, we need to look through a telescope.
The word telescope means “see far,” and that is just what a telescope enables us to do.
The Italian scientist, Galileo Galilee, was the first person to study the heavens through a telescope, in 1609.
Galileo made his telescope using glass lenses. Some astronomers still use this type of telescope today. It is called a refractor, because the lenses refract, or bend, light into the telescope. But the biggest and most powerful telescopes use mirrors to gather the starlight. They are called reflectors, because the mirrors reflect light into the telescope.
Up in the mountains
The places where astronomers work are called observatories. You find most observatories high up in the mountains. Here, the air is thin and clear, so the light can reach the telescope more easily. There is also less interference from the glare of city lights. At an observatory, the telescopes are kept in large buildings with dome-shaped roofs. Part of the dome slides back at night so that the telescope is uncovered. The dome swivels around so that it can point at any part of the sky. The world’s biggest reflecting telescope, in the Soviet Union, has a mirror 20 feet (6 meters) across. It could detect the light of a candle 15,500 miles (25,000 kilometers) away!
How to make a Telescope at Home
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