Telescopes - research into types and properties of telescopes

The first 200 words of this essay...

Telescopes are instruments that magnify distant objects. Astronomers use telescopes to study the planets, stars, and other floating bodies. In most telescopes a lens or mirror is used to form an image of an object. The image may be viewed through an eyepiece or recorded on photographic film or by electronic devices. Telescopes produce images of objects too far away to be seen by the unaided human eye. The Dutch optician Hans Lippershey designed the first telescope in 1608, when he mounted two glass lenses in a narrow tube. Within a year the Italian astronomer Galileo built a similar device and became the first person to use a telescope to study the sky.

Optical Telescopes

Optical Telescopes use a lens or mirror to collect and focus light waves. There are three main types of optical telescopes.

Refracting telescope

Refracting telescopes also known as refractors have a large lens called an objective lens at one end of a long, narrow tube. The lens is convex on both sides so that the middle of the lens is thicker than the edges. The glass slows the light rays as they pass through the lens. (A wave is