Telescopes Telescopes are the main tools of astronomers and have been used since the days of Galileo to study objects in the sky. Of course since there are different types of light, there are also different types of telescopes. Regardless of the differences, telescopes have three purposes: 1. To collect light. Believe it or not, this is the most important purpose. As we like to say in astronomy "Size does matter - the bigger, the better." In fact, size can make all the difference. You may want to think of a telescope as a light bucket and the more light it collects, the better the view. The amount of light a telescope collects depends directly upon the size of the light collecting surface - the part of the telescope that gathers up the light. The light gathering ability goes as the radius of the light gathering surface squared, since telescopes usually have a circular light gathering surface and the size of this surface is a function of radius squared (Area of a circle= R 2 ). If you were to double the radius,
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