Tools of the Astronomer

The Telescope of the Astronomer

Years and Years ago, astronomers didn't have the advantage of the telescope. They could only use their naked eye. It wasn't until Galileo first made a better telescope that it could be used for looking into space. Most every telescope you buy today is better than the one he used. These telescopes have revolutionized astronomy in general.

When Galileo first took his telescope and looked at the sky he saw amazing things. He saw craters on the Moon, dark spots on the surface of the Sun, tiny moons moving around Jupiter. No one else had ever seen these things. With the modern telescopes we use today, we can see many many more things.

Light from planets, stars and galaxies spreads itself on Earth, and a telescope collects this light and lets us look at the object the light came from. Some telescopes, called refracting telescopes, collect and focus light through a glass lens. Another type, the reflecting telescopes, reflect light on a glass mirror. The bigger the telescope the more light it collects, giving us a better view of what we want to look at. Some don't have just one big mirror, it has many little mirrors that fit together like bathroom tile. With the help of a computer, these little mirrors work together like one big mirror. The Hubble Space Telescope is the largest orbiting optical telescope in history.

The refracting and reflecting telescopes collect and focus visible light, which is light that we can see. There are also other types of light that we cannot see. Nowadays astronomers have telescopes to looks at different types of light. On Earth we can look at visible light and radio waves. A few of the very largest telescopes look for radio light. Other types of light, like X-ray light and ultraviolet light, can only be looked at from space, so astronomers have built telescopes in space that orbit the Earth. The most famous is the Hubbell Space Telescope.