Telescopes

Since telescopes were invented around 200 years ago we have had a better view of objects in the sky and our understanding of the cosmos has increased enormously, and is still increasing.

There are two main types of optical telescope. Each has advantages and disadvantages.

This is a REFRACTING telescope

It uses lenses to bend the light to form an image.

They tend to be more portable as they are smaller an lighter. They are less likely to need fixing.

This is a REFLECTING telescope

It uses a large mirror to focus the light.

They usually have a higher magnifying power for the same money.

The hole at the front (the aperture) is larger so they collect more light giving a brighter, sharper image.

There are some other telescopes worth mentioning.

	This is the Hubble Space Telescope It is bigger than a double-decker bus and is in orbit around the Earth, like a satellite. Because it is above the Earth's atmosphere it takes fantastic pictures giving us the best view of the cosmos that we have ever had.
	This is the Lovell telescope at Jodrell Bank in England. It is a very large radio telescope. Stars and galaxies don't just emit light and a lot can be learnt by examining the other wavelengths that they emit.
	This is the Gemini South telescope in Chile. Being on top of a mountain means that it is above much of the Earth's atmosphere. It is also well away from any man-made pollution (including light pollution) that would spoil the view of the stars.
	This is a good pair of binoculars If you are interested in astronomy you should buy a pair of these before you pay a lot of money for a fancy telescope. You'll be amazed at how much more you can see.