Fluency Unit 5 Assessment

When scientists look at the moon, planets, and stars,

they use a telescope. It is one of the most important

scientific instruments. Many people have a telescope

at home. They can watch the night skies whenever

they want.

There are two kinds of telescopes. One uses a lens to

gather light and is called a refracting telescope. The other

uses mirrors and is called a reflecting telescope.

The refracting telescope was invented around 500 years

ago. No one is sure who invented it because a number

of people were using lenses made of glass. The famous

Italian astronomer Galileo is one possibility. He may

have been the first person to make a telescope and use

it to look at the moon, planets, and stars. He made

several telescopes, and you can still see them in a

museum in Italy.

The reflecting telescope was invented a little later.

Scientists knew that curved mirrors changed the way

things were seen. The scientist Isaac Newton may have

been the first person to make a reflecting telescope. He

built it during the sixteen hundreds.

The telescopes that astronomers use today are more

powerful than those used long ago. In fact, the telescope

that you can buy at a local store or online is more

powerful than the ones used by Galileo or Newton.

The most powerful telescopes today are huge and are

kept in special buildings. The buildings are usually on top

of a mountain. This is a good location for a telescope.

There are no city lights around, and the air is a little

cooler and clearer. One of the most famous telescopes is

the Hubble Space Telescope. This is in orbit around Earth

and sends the pictures it takes of the stars back to Earth.