A telescope (from the Greek tele = 'far' and skopein = 'to look or see'; teleskopos = 'far-seeing') is an optical tool which gathers and focuses electromagnetic radiation. Telescopes increase the apparent angular size of distant objects, as well as their apparent brightness. Telescopes are used for astronomy and in many non-astronomical instruments including theodolites, transits, spotting scopes, monoculars, binoculars, camera lenses and spyglasses. The word "telescope" usually refers to optical telescopes, but there are telescopes for mo ...

Including:

• Telescope - History
• Telescope - Types
• Telescope - Telescope mountings
• Telescope - Research telescopes
• Telescope - Imperfect images
• Telescope - The five Seidel aberrations
• Telescope - The chromatic aberrations
• Telescope - Famous optical telescopes
• Telescope - Related lists

Read more here: » Telescope: Encyclopedia - Telescope

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Telescope, Telescope - History, Telescope - Types, Telescope - Telescope mountings, Telescope - Research telescopes, Telescope - Imperfect images, Telescope - The five Seidel aberrations, Telescope - The chromatic aberrations, Telescope - Famous optical telescopes, Telescope - Related lists

Read more here: » Telescope: Encyclopedia II - Telescope - Research telescopes

Most large research telescopes can operate as either a cassegrain telescope (longer focal length, and a narrower field with higher magnification) or newtonian telescope (brighter field). They have a pierced primary, a newtonian focus, and a spider to mount a variety of replaceable secondaries. A new era of telescope making was inaugurated by the MMT, with a mirror composed of six segments synthesizing a mirror of 4.5 metres diameter (this has now been replaced by a single 6.5m mirror). Its example was followed by ...

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Telescope, Telescope - History, Telescope - Types, Telescope - Telescope mountings, Telescope - Research telescopes, Telescope - Imperfect images, Telescope - The five Seidel aberrations, Telescope - The chromatic aberrations, Telescope - Famous optical telescopes, Telescope - Related lists

Read more here: » Telescope: Encyclopedia II - Telescope - Research telescopes

LONEOS uses a 0.6-meter f/1.8 Schmidt telescope, which was aquired from Ohio Weslayan University in 1990, and a 16 megapixel CCD detector that gives a wide field of view of 3.17 by 1.58 degrees of the sky. It has a nightly scan rate of about 1,000 square degrees. (The camera can cover the entire visible sky in about a month.) The CCD has detected asteroids as faint as visual magnitude 19.8. < ...

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Lowell Observatory Near-Earth-Object Search, Lowell Observatory Near-Earth-Object Search - Telescope, Lowell Observatory Near-Earth-Object Search - CCD camera, Lowell Observatory Near-Earth-Object Search - Camera management, Lowell Observatory Near-Earth-Object Search - Computers, Lowell Observatory Near-Earth-Object Search - Software, Lowell Observatory Near-Earth-Object Search - Observing site, Lowell Observatory Near-Earth-Object Search - The LONEOS dome, Lowell Observatory Near-Earth-Object Search - Press releases, Lowell Observatory Near-Earth-Object Search - May 20 2004, Lowell Observatory Near-Earth-Object Search - October 15 2003, Lowell Observatory Near-Earth-Object Search - October 3 2003, Lowell Observatory Near-Earth-Object Search - August 14 2001, Lowell Observatory Near-Earth-Object Search - LONEOS scientific staff

Read more here: » Lowell Observatory Near-Earth-Object Search: Encyclopedia II - Lowell Observatory Near-Earth-Object Search - Telescope

The first telescopes may have been Assyrian crystal lenses. Article Though the Visby lenses tentatively suggest that the technology was known to the Arabs and then to the Vikings in the 10th century, credit for assembling the first telescope is usually given to an unknown Dutch spectacle maker in about 1608. Some name that person as Hans Lippershey (c1570-c1619). Even if Lippershey did not make the first one, he publicized it. Galileo Galilei made his own telescope in 1609, calling it at first a perspicillum, and then using the ...

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Telescope, Telescope - History, Telescope - Types, Telescope - Telescope mountings, Telescope - Research telescopes, Telescope - Imperfect images, Telescope - The five Seidel aberrations, Telescope - The chromatic aberrations, Telescope - Famous optical telescopes, Telescope - Related lists

Read more here: » Telescope: Encyclopedia II - Telescope - History

The first telescopes may have been Assyrian crystal lenses. Article The Visby lenses tentatively suggest that the technology was known to the Arabs and Persians then to the Vikings in the 10th century. Leonard Digges is sometimes credited with the invention in England in the 1570s, but usually credit for assembling the first telescope is usually given to an unknown Dutch spectacle maker in about 1608. Some name that person as Hans Lippershey (c1570-c1619), but Jacob Metius and Zacharias Jansen also claimed to have invented a telescope ...

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Telescope, Telescope - History, Telescope - Types, Telescope - Telescope mountings, Telescope - Research telescopes, Telescope - Imperfect images, Telescope - The five Seidel aberrations, Telescope - The chromatic aberrations, Telescope - Famous optical telescopes, Telescope - Related lists

Read more here: » Telescope: Encyclopedia II - Telescope - History

There is a strong tradition of amateur telescope making within the amateur astronomy community. The classic amateur telescope is the Newtonian reflector with a dobsonian type mount, also known as a "Dobsonian telescope." Some also build refractors and a very few attempt compound designs such as the Maksutov telescope. Amateur telescope makers typically make the most critical parts of ...

Including:

• Amateur telescope making - Telescope design
• Amateur telescope making - Mirror making
• Amateur telescope making - Grinding
• Amateur telescope making - Polishing
• Amateur telescope making - Mirror testing
• Amateur telescope making - Figuring the mirror
• Amateur telescope making - Aluminizing or silvering the mirror
• Amateur telescope making - Telescope construction
• Amateur telescope making - Tube
• Amateur telescope making - Mount
• Amateur telescope making - Telescope making books and other published information

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The Very Large Telescope Project (VLT) consists of a system of four separate optical telescopes (the Antu telescope, the Kueyen telescope, the Melipal telescope, and the Yepun telescope) organized in an array formation. Each telescope has an 8.2 m aperture. The project is organized by the European Southern Observatory. VLT is located at the Paranal Observatory on Cerro Paranal, a 2,635 m high mountain in the Atacama desert in northern Chile. Very Large Telescope - General informa ...

Including:

• Very Large Telescope - General information
• Very Large Telescope - Interferometry and the VLTI

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An Altazimuth or alt-azimuth mount is a simple mount used for moving a telescope or camera along two perpendicular axes of motion. The vertical movement is known as the altitude, while the horizontal motion is called the azimuth. The biggest advantage of alt-azimuth mounts is their simplicity in both manufacture and use. They are often used for beginner telescopes, or for spotting scopes, but are still widely in use for more advanced telescopes. In the latter case, advanced electronics and motors are sometimes attached to com ...

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First developed in 1672 by Laurent Cassegrain, a Cassegrain Telescope this type of reflector is a combination of a prime concave and a secondary convex mirror, both aligned axially. The prime mirror usually contains a hole in the centre thus permitting the light to reach an eyepiece, a camera, or a light detector. Concave Mirror: Paraboloid type Convex Mirror: Hyperboloid type A Cassegrain reflecting telescope consists of primary and secondary reflecting mirrors. In a traditional Newtonian reflector ...

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The Multi-Element Radio Linked Interferometer Network (MERLIN) is an array of radio telescopes spread across Britain. The array is run from Jodrell Bank Observatory in Cheshire by the University of Manchester on behalf of PPARC as a National Facility. The array consists of up to seven radio telescopes and includes the Lovell Telescope, MkII, Cambridge, Defford, Knockin, Darnhall and Pickmere (previously known as Tabley). The longest baseline is therefore 217km and MERLIN can operate at frequencies between 151 MHz and 24 ...

Including:

• MERLIN - History
• MERLIN - The e-MERLIN upgrade
• MERLIN - Telescope information

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An observatory is a location used for observing terrestrial and/or celestial events. Astronomy, astrology, climatology, geology, meteorology and volcanology are examples of disciplines for which observatories have been constructed. Historically, observatories were as simple as containing a sextant (for measuring the distance between stars) or Stonehenge (which has some alignments on astronomical phenomena). Modern astronomical observatories typically contain one or more permanently mounted telescopes contained in buildings with a rota ...

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Amateur astronomy, often called back yard astronomy, is a hobby whose participants enjoy observing celestial objects. It is usually associated with viewing the night sky when most celestial objects and events are visible, but sometimes amateur astronomers also operate during the day for events such as sunspots and solar eclipses. Amateur astronomers often look at the sky using nothing more than their eyes, but common tools for amateur astronomy include portable telescopes and binoculars. Amateur astronomy - ...

Including:

• Amateur astronomy - Amateur astronomy and scientific research
• Amateur astronomy - Societies for amateur astronomy
• Amateur astronomy - Approaches to using amateur telescopes
• Amateur astronomy - Star hopping
• Amateur astronomy - GOTO telescopes
• Amateur astronomy - Comparing methodologies
• Amateur astronomy - Additional tools and activities
• Amateur astronomy - Beginning in amateur astronomy
• Amateur astronomy - Beginning with a GOTO telescope
• Amateur astronomy - Becoming acquainted with the night sky
• Amateur astronomy - Suggested reading

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The Arecibo Observatory is located in Arecibo, Puerto Rico on the north coast of the island. It is operated by Cornell University under cooperative agreement with the National Science Foundation. The observatory works as the National Astronomy and Ionosphere Center (NAIC) although both names are officially used to refer to it. The observatory's radio telescope is the largest single-aperture telescope ever to be constructed. (Compare "multiple aperture telescope".) It collects radio astronomy, terrestrial aeronomy, ...

Including:

• Arecibo Observatory - General information
• Arecibo Observatory - Design and architecture
• Arecibo Observatory - Discoveries
• Arecibo Observatory - Usage
• Arecibo Observatory - Arecibo in popular culture

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Angular resolution describes the resolving power of a telescope. Angular resolution - Definition of terms. Resolving power is the ability of a microscope or telescope to measure the angular separation of images that are close together. Resolution is the minimum distance between distinguishable objects, in microscopy. These terms also apply to other angle and position measuring devices. Resolution, more generally, is the precision of any instrument to measure a continuous variable ...

Including:

• Angular resolution - Definition of terms
• Angular resolution - Explanation
• Angular resolution - Telescope case
• Angular resolution - Microscope case

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The historical sequence of events now brings us to the discovery of the achromatic telescope. The first person who succeeded in making achromatic refracting telescopes seems to have been Chester Moor Hall, a gentleman of Essex. He argued that the different humours of the human eye so refract rays of light as to produce an image on the retina which is free from colour, and he reasonably argued that it might be possible to produce a like result by combining lenses composed of different refracting media. After devoting some time to the i ...

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History of telescopes, History of telescopes - Refracting telescopes, History of telescopes - Reflecting telescopes, History of telescopes - Achromatic Telescope, History of telescopes - Related links

Read more here: » History of telescopes: Encyclopedia II - History of telescopes - Achromatic Telescope

There is an archeological finding of lenses is from Gotlandia in Sweden. These so-called Visby lenses can be dated to the second half of the 11th century. The one half is near a perfect ellipsoid and the other flat, making a perfect tool for handling light beams. Some of these lenses have a silver mounting and have been used as pendants. There are also unmounted lenses that may have been used as a loupe. They have been speculated to be components from an ancient telescope. However, if it would be, maybe it was something imported fro ...

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History of telescopes, History of telescopes - Refracting telescopes, History of telescopes - Reflecting telescopes, History of telescopes - Achromatic Telescope, History of telescopes - Related links

Read more here: » History of telescopes: Encyclopedia II - History of telescopes - Refracting telescopes

Until Newton's discovery of the different refrangibility of light of different colours, it was generally supposed that object-glasses of telescopes were subject to no other errors than those which arose from the spherical figure of their surfaces, and the efforts of opticians were chiefly directed to the construction of lenses of other forms of curvature. James Gregory, in his Optica Promota (1663), discusses the forms of images and objects produced by lenses and mirrors, and shows that when the surfaces of the lenses or mirrors are p ...

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History of telescopes, History of telescopes - Refracting telescopes, History of telescopes - Reflecting telescopes, History of telescopes - Achromatic Telescope, History of telescopes - Related links

Read more here: » History of telescopes: Encyclopedia II - History of telescopes - Reflecting telescopes

Nearly all large research-grade astronomical telescopes are reflectors. Some reasons are: In a lens the entire volume of material has to be free of imperfection and inhomogeneities, whereas in a mirror, only one surface has to be perfectly polished. Light of different colors travels through a medium other than vacuum at different speeds. This causes chromatic aberration. There are technical difficulties involved in manufacturing and manipulating large-aperture lenses. One of them is that all real materials sag ...

See also:

Optical telescope, Optical telescope - How it works, Optical telescope - Angular resolution, Optical telescope - Focal length and f-ratio, Optical telescope - Light-gathering power, Optical telescope - Research telescopes

Read more here: » Optical telescope: Encyclopedia II - Optical telescope - Research telescopes

For detailed information on specific designs of reflecting and refracting telescopes, see the main articles on Reflecting telescopes and Refracting telescopes. The basic scheme is that the primary light-gathering element, the objective (objective lens (1) or concave mirror), focuses light from a distant object (4) to a focal plane where it forms a real image (5). This image is viewed through an eyepiece (2), which acts like a magnifying glass. The eye (3) sees ...

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Optical telescope, Optical telescope - How it works, Optical telescope - Angular resolution, Optical telescope - Focal length and f-ratio, Optical telescope - Light-gathering power, Optical telescope - Research telescopes

Read more here: » Optical telescope: Encyclopedia II - Optical telescope - How it works