Essay On Telescope Essay

Telescopes are commonly used and discussed by people in everyday life. They are instruments that were created to gather and focus light from a certain part of the ‘electromagnetic spectrum’. They generally are referred to when talking about wavelengths of light that can be seen by the human eye. These wavelengths are most commonly magnified and are studied ‘optically’, hence the name, optic telescopes. However there is a different type of telescopes that cannot be seen by the naked eye known as non-optical telescopes.

There are three main types of optical telescopes: refracting, reflecting, and catadioptric telescope, although catadioptric is not very common, and is usually just refracting and reflecting. In all optical telescopes, there is

This first telescope (Figure 1) is 75m across and was built in the late 1950’s. The largest radio telescope in the world is in Puerto Rico and is built between some small hills that had a roughly parabolic valley. It is 300m across.

As shown below (Figure 2), radio telescopes work very simply having a parabolic dish reflecting radio waves onto an antenna at the principal focus. The radio waves are very weak, and the focusing by the reflector makes them much more intense. The signal is then passed down through very high quality amplifiers and then analysed by a computer.

So this means that a bigger dish will collect more photons and energy from an object in a given amount of time and therefore can detect fainter objects.

This formula explains that the gathering power is proportional to the area. So a bigger dish collects more photons and energy in a given time.

There are a few main similarities between these two types of telescopes:

 The use of a parabolic dish in radio telescopes is equivalent to an objective mirror in normal optical telescopes.

 Radio telescopes have an antenna. This is used as a detector at principal focus rather than having a camera or eye