What Is an Astro Telescope?
An astro telescope is a device astronomers use to collect far more light than the unaided eye can gather. The telescope brings the light to a small focus where it can be studied. Telescopes magnify images, enabling astronomers to distinguish detail and visually separate distant objects from one another. Galileo, an Italian physicist was the first person to use a telescope to observe the sky in 1609. Astronomical observatories around the world use different kinds of telescopes.
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How They Work
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Optical telescopes use lenses or mirrors to gather and focus starlight. This is the primary objective lens, which is also known as the primary mirror. The primary lens captures light from celestial objects and focuses it back on a point to form a "real image." The image is then captured by the telescope's camera. This image may be enhanced by a series of lenses known as the eyepiece. Usually, telescopes are kept in buildings with domed roofs that can be opened for a clear view of the sky.
Refracting Telescope
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The refracting telescope, or refractor, has two lenses. The objective lens, which is the larger of the two, forms the first image inside the telescope and is located at the front of the tube. It gathers starlight and bends or refracts the rays of the light to form an image at the rear of the tube. The smaller eyepiece lens magnifies the image. The Yerkes Observatory in Williams Bay, Wisconsin, is an example of a refracting telescope.
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Reflecting Telescope
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A reflector telescope, or reflecting telescope, uses one large, curved mirror to gather and focus starlight. The objective mirror is located at the bottom of the telescope tube. When the tube is pointed at a star, a small image forms near the top of the tube. A smaller mirror (an eyepiece lens) magnifies the image for the observer. The Hale telescope on Palomar Mountain in California is an example of a reflecting telescope.
Multiple-Mirror Reflectors
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The multiple-mirror telescope, or MMT, is a device in which several mirrors are used instead of a single large mirror. When the light from each of these individual mirrors combines and focuses on a single point, it forms an image. The first MMT was built on Mount Hopkins in Arizona.
Other Optical Telescopes
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Schmidt telescopes are telescopes that use both refracting and reflecting lenses and have a wide field of view.
Hubble is the world's first space-based optical telescope named after Edwin P. Hubble, an American astronomer. Because it is positioned in space, Hubble is not affected by earth's atmospheric interference while capturing light from celestial objects. Hubble's main mirror captures the light and reflects it to the secondary mirror. The secondary mirror then reflects the light through a path which leads to the center of the primary mirror. This light is finally enhanced by the instruments in the telescope.
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References
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- Photo Credit refractor telescope image by Jim Mills from Fotolia.com
