Telescopes

    Heavenly objects like stars, galaxies, nebulae, and others are very far away from the earth. As we have learned, light takes many years to reach the earth. This is why we only see bright dots in the sky. But these stars are not this small. some of the stars are the size of the solar system. To see them more closely or to observe them more deeply, We need telescopes.

     Stars like our Sun emit all types of rays. Not all of them reach the surface of the earth. Most of the rays which are harmful to life such as UV rays, x-rays, etc. are stopped in the atmosphere itself. With a narrow band of the visible spectrum, radio waves can also pass through the earth's atmosphere. 

The part Spectrum which reaches the earth.

    As you can see that only visible, visible, infrared, and radio waves can enter the atmosphere therefore only a small part of the light comes from the stars we can see. 

   Optical telescopes are useful when the light is in the colors. Devasthal Optical Telescope (DOT) is the largest optical telescope in India. And the world's largest telescope is in Hawaii island named the Keck telescope with a diameter of 10 meters.

Keck Observatory, U.S.A., Hawaii

    Radio waves have a very large wavelength. It varies from some meters to kilometers. So the telescope must be that large. India's largest Radio telescope is in the Khodad, Pune. Which contains 24 dishes from almost 3-story buildings spread over 100 acres of area.

Devasthal Optical Telescope

                       

GMRT (Giant Meter wave Radio Telescope) Pune

       There are several more telescopes in the world such as The square kilometer array Observatory, in Australia, the Effelsberg radio telescope in Germany, and others.

        The rays cannot reach the surface of the earth, and cannot be observed from the ground. We need to go to space to observe them. To achieve this aim many telescopes are launched into space, and they revolve around the earth as satellites. The famous Hubble space telescope is one of them. Hubble telescope can sense light from ultraviolet to near-infrared. Hubble belongs to NASA. There are several more gamma-ray telescopes and x-ray telescopes in space in different countries.

Chandra X-ray observatory of NASA

Telescopes is very important to study the universe because the light is the only thing that we receive from space and nothing else and we need to collect and study it as much as possible. And also we need to build bigger telescopes. we will solve more mysteries of the world using these telescopes.