What are Telescopes

What are Telescopes

History of Telescopes

Tips On Using Telescopes

Frequently Asked Questions


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Telescope is a wonderful invention in the world of astronomy and science. The word telescope has a Greek origin and is derived from teleskopos, meaning 'far-seeing'. When you mention a telescope in every day life, you usually refer to an optical telescope.

Have you ever wondered how telescopes work? Right from astronomy, which perhaps is the most popular use of optical telescopes, it is also used for different purposes. Your pair of binoculars, theodolites, spotting scopes, monoculars, camera lenses and even spyglasses, all use optical telescopes.

Telescopes originated when scientists discovered the properties of light to deviate from its original path as it passes from one medium to another, also known as refraction. This ability of a lens to redirect light to a desired point is what lies behind the basic telescopic invention. Scientists are known to have used lenses with variable diameters and focal lengths to achieve desired visuals magnification of objects in the universe.

Optical telescopes are mainly divided into,

Refracting Telescopes:

Refracting telescopes use different lenses. As the name suggests, it makes use of refractive properties of light and is used for terrestrial and astronomical screening. In refraction, the parallel rays of light are passed through a convex lens that refracts and converges at a focus. The image at the focus is then observed using small magnifying lenses called the eyepiece.

Reflecting Telescopes:

Reflecting telescopes are made using mirrors and lenses. It uses the reflective properties of light which is helpful for astronomical viewing. In this case, we use the reflective property of light rays that converge parallel rays of light at the center using a concave reflector/mirror that is magnified using an eyepiece lens. Once the light gets focused at the prime focus, the image here is carried to a convenient location for observation using various systems of auxiliary mirrors and lenses.

It is interesting to note that there is no telescope that can develop a precise image. Aperture diffraction causes both reflecting and refracting telescopes to fail in precision. In practice, flawless mirrors and lenses do not exist, so image aberrations and aperture diffraction are unavoidable.

Radio Telescopes:

These telescopes do not use lens or optical device. Radio telescope makes use of radio signals from different sources in the universe. It all began when Karl G Jansky detected radio waves from a cosmic source in the central region of the Milky Way Galaxy. Radio Telescopes help us detect and map waves beyond visible light, which is just a small part of the Electromagnetic spectrum. Radio Telescopes also follow the same principle of converging vast range of radio frequency to a point and then using this data to map the sources and composition of such signals.

Telescopes have tremendously contributed to our knowledge and learning of the universe. With advanced technologies, we have been able to map the solar system with more precision than ever before.

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