Written by Beth Hrusch
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Telescopes are designed to magnify objects that are at a distance. The lens on a telescope gathers more light than the human eye can on its own. Most distant objects are so small that they do not take up much room on the retina, and the eye therefore can't see the details. The telescope acts in two ways to take small images and make them large enough for the eye to see these fine points.

Telescopes Enhance Long-Distance Viewing

There are two basic kinds of telescope, reflector and refractor. Refractors use glass lenses and reflectors use mirrors. Both achieve the same result. Magnification occurs when the lens or mirror gathers light into a point or focus. An eyepiece then takes that light and spreads it out, thus "magnifying" the image. Reflector designs, by using mirrors, eliminate chromatic aberration, the rainbow effect that sometimes occurs with lenses.

Telescopes are generally specialized for their purpose. Their ability to collect light and their power of magnification depends upon the way they are constructed. A telescope with a larger diameter lens-a larger aperture-can gather more light and produce a sharper image. Magnification depends upon the combination of lenses or mirrors used. Thus, an astronomy telescope would be expected to have a larger aperture and greater magnification in order to see very distant objects.

Telescopes have been around since about 1608, when the first refractor telescope was invented. Since then, people have relied upon them to reveal the details of the world and the universe they live in. The telescope is responsible for scientific discoveries that have changed the course of human history and helped illuminate the great mysteries of the natural world. It is a simply constructed yet very powerful tool in the quest for understanding.

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