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

See also:

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 - Types

The telescopes are broadly classified into two main categories. Optical telescopes Radio telescopes The optical telescopes are again divided into two Galilean refracting telescopes Newtonian reflecting telescopes The Galilean or refracting telescopes used refraction property of light. They were made up of lenses. They can be used for both terrestrial as well as astronomical viewing. The Newtonian or reflecting telescopes used reflec ...

See also:

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 - Types

A crane is a tower or derrick equipped with cables and pulleys that is used to lift and lower materials. Cranes are commonly used in the construction industry and in manufacturing heavy equipment. Construction cranes are usually temporary structures, either fixed to the ground or mounted on a purpose-built vehicle. Cranes may either be controlled from an operator in a cab that travels with the crane, by a pushbutton pendant control station, or by infrared or radio control. Where a cab operator is employed, workers on the ground will c ...

Including:

• Crane machine - Types of cranes
• Crane machine - Ancient cranes
• Crane machine - Medieval cranes
• Crane machine - Mobile crane
• Crane machine - Telescopic crane
• Crane machine - Tower crane
• Crane machine - Truck-mounted Crane
• Crane machine - Rough Terrain Crane
• Crane machine - Crawler Crane
• Crane machine - Loader crane
• Crane machine - Gantry crane
• Crane machine - Overhead crane
• Crane machine - Stacker crane
• Crane machine - Floating crane
• Crane machine - Mechanical principles
• Crane machine - Cranes of special interest

Read more here: » Crane machine: Encyclopedia - Crane machine

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

Read more here: » Amateur telescope making: Encyclopedia - Amateur telescope making

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 ...

Read more here: » Cassegrain Reflector: Encyclopedia - Cassegrain Reflector

A microscope (Greek: micron = small and scopos = aim) is an instrument for viewing objects that are too small to be seen by the naked or unaided eye. The science of investigating small objects using such an instrument is called microscopy, and the term microscopic means minute or very small, not easily visible with the unaided eye. In other words, requiring a microscope to examine. The most common type of microscope—and the first to be invented—is the optical microscope. This is an optical instrument containing one or more lenses that produce an enlarged image of an ...

Including:

• Microscope - Simple optical microscope
• Microscope - Compound optical microscope
• Microscope - Stereo microscope
• Microscope - Special designs
• Microscope - Optical resolution
• Microscope - History of the microscope
• Microscope - Other types of microscopes

Read more here: » Microscope: Encyclopedia - Microscope

Anti-reflective or antireflection (AR) coatings are a type of optical coating applied to lenses and other devices to reduce reflection from optical surfaces. This often improves the efficiency of the system; this is especially important if the light wasted by reflections is difficult to obtain, i.e. from a large telescope, an obstacle on a dark roadway, or an intricate optics experiment. They also have qualitative benefits like making the eyes of a glasses-wea ...

Read more here: » Anti-reflective coating: Encyclopedia - Anti-reflective coating

Aperture synthesis is a type of interferometry that mixes signals from a collection of instruments to produce measurements having the same angular resolution as an instrument the size of the entire collection. At each separation and orientation, the lobe-pattern of the interferometer produces an output which is one component of the Fourier transform of the spatial distribution of the brightness of the observed object. In order to produce a high quality image, a large number of different separations between different telescopes are req ...

Including:

• Aperture synthesis - External links

Read more here: » Aperture synthesis: Encyclopedia - Aperture synthesis

Gamma Virginis (γ Vir / γ Virginis) is a star in the constellation Virgo. It also has the traditional name Porrima. Gamma Virginis is a binary star, consisting of two stars of approximately equal apparent magnitudes 3.48 and 3.50, and of spectral type F0V. With an orbital period of 168.68 years (calculated by Heintz at Sproul Observatory in 1990) until the beginning of the 1990s it was an easy object for amateur astronomers, but now the smaller apparent distance between the stars requires a larger telescope. The last t ...

Including:

• Gamma Virginis - Changes of distance and position angle

Read more here: » Gamma Virginis: Encyclopedia - Gamma Virginis

1036 Ganymed is the largest Amor asteroid. It was discovered by Walter Baade on October 23, 1924 and is named after Ganymede, the beautiful youth with whom Zeus fell in love. Ganymed is about 32 km in diameter and is an S-type asteroid, meaning that it is highly reflective and composed of nickel-iron mixed with iron- and magnesium-silicates. It is also a Mars-crosser asteroid. In 1998, a radar study of Ganymed by the Arecibo radio telescope produced some images of the asteroid's shape. Although not very detailed, the images reveal a roughly spherical object. One occultation of a star by Ganym ...

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Trumpet List of classical trombonists List of jazz trombonists A lip-reed aerophone with a predominantly cylindrical bore, the trombone is a musical instrument in the brass family. The most frequently encountered trombones are the tenor and bass counterparts of the trumpet. The trombone is usually characterised by a telescopic slide with which the player varies the length of the tube. The word trombone derives from Italian tromba (trumpet) - and -one (a suffix meaning large). Thus, quite ...

Including:

• Trombone - Construction
• Trombone - History
• Trombone - Renaissance & Baroque periods
• Trombone - Classical period
• Trombone - Romantic Period
• Trombone - 20th Century
• Trombone - Types of trombone
• Trombone - Tenor trombone
• Trombone - Bass trombone
• Trombone - Contrabass trombone
• Trombone - Alto trombone
• Trombone - Soprano trombone
• Trombone - Sopranino and piccolo trombones
• Trombone - Valve trombone
• Trombone - Technique
• Trombone - Notation
• Trombone - Mutes
• Trombone - Variations in construction
• Trombone - Bells
• Trombone - Valve attachments
• Trombone - Tuning
• Trombone - Slides
• Trombone - Regional variations
• Trombone - Selective Bibliography

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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

Read more here: » Amateur astronomy: Encyclopedia - Amateur astronomy

Astronomical seeing refers to the blurring and twinkling of astronomical objects such as stars caused by the Earth's atmosphere. The astronomical seeing conditions on a given night at a given location describe how much the Earth's atmosphere perturbs the images of stars as seen through a telescope. The most common seeing measurement is the diameter (technically Full Width Half Maximum) of the seeing disc. The seeing disc diameter ("seeing") is a reference to the best possible angular resolution which can be achiev ...

Including:

• Astronomical seeing - The Effects of Astronomical Seeing
• Astronomical seeing - Measures of Astronomical Seeing
• Astronomical seeing - The FWHM of the seeing disc
• Astronomical seeing - r0 and t0
• Astronomical seeing - The CN2 profile
• Astronomical seeing - Overcoming Atmospheric Seeing

Read more here: » Astronomical seeing: Encyclopedia - Astronomical seeing

Antiope is classified as a member of the Themis family of asteroids. One observed stellar occultation by Antiope has been reported, on (June 11, 1980). In 2000, using adaptive optics at the Keck Telescope on Mauna Kea it was discovered that Antiope is in fact a double asteroid, consisting of two individual bodies (the "secondary" is designated S/2000 (90) 1), each about 110±16 km across, separated by only 170 kilometers, orbiting around a common center. This means the gap separating the two halves is a mere 60±16 km. A ...

Read more here: » 90 Antiope: Encyclopedia - 90 Antiope

3 Juno (jew'-noh) was the third asteroid to be discovered and is one of the largest main belt asteroids. It was was discovered on September 1, 1804 by German astronomer Karl L. Harding, using a humble 2-inch telescope. It was named after the mythological figure Juno, the highest Roman goddess. The adjectival form of the name is Junonian. 3 Juno - Characteristics. Juno is close to being the seventh largest asteroid (it cannot currently be ranked relative to 52 Europa, with a mass approximately ...

Including:

• 3 Juno - Characteristics
• 3 Juno - Observations
• 3 Juno - Aspects

Read more here: » 3 Juno: Encyclopedia - 3 Juno

A barred spiral galaxy is a spiral galaxy with a band of bright stars emerging from the center and running across the middle of the galaxy. Spiral arms appear to emerge from the ends of the "bar" in these galaxies, whereas they appear to emerge directly from the core in ordinary spiral galaxies. Edwin Hubble classified these types of spiral galaxies as "SB" ("Spiral", "Barred"), and arranged them into three sub-categories based on how open the arms of the spiral are. SBa types feature tightly bound arms, while SBc types are at ...

Including:

• Barred spiral galaxy - Examples

Read more here: » Barred spiral galaxy: Encyclopedia - Barred spiral galaxy

Very Long Baseline Interferometry (VLBI) is a type of interferometry in which the data received at each antenna in the array is paired with timing information, usually from a local atomic clock, and then stored for later analysis on magnetic tape or hard disk. At that later time, the data are correlated with data from other antennas similarly recorded, to produce the resulting image. The resolution achievable using interferometry is proportional to the distance between the antennas furthest apart in the array. The VLBI technique enabl ...

Including:

• Very Long Baseline Interferometry - Space VLBI
• Very Long Baseline Interferometry - How VLBI Works

Read more here: » Very Long Baseline Interferometry: Encyclopedia - Very Long Baseline Interferometry

A reflecting telescope is constituted not of lenses but of mirrors. It being less costly to manufacture, one can, for the price of a refracting telescope, acquire an instrument of the more important diameter that gives access to the deep space. Nevertheless, to take advantage of the power of a reflecting telescope, it is necessary to have a good site of observation safe from the lights of the city, otherwise the usage of a good telescope is preferable. With a 150mm lensed reflecting telescope, the viewer is able to distinguish the spi ...

See also:

Skygazing, Skygazing - Naked eye skygazing, Skygazing - Diurnal observation, Skygazing - Nocturnal observation, Skygazing - Binocular gazing, Skygazing - Choice of binoculars, Skygazing - Advice on observational techniques, Skygazing - Observations with a refracting telescope, Skygazing - Choice of the refracting telescope, Skygazing - Advice of usage, Skygazing - The observation with a reflecting telescope, Skygazing - Types of reflecting telescope

Read more here: » Skygazing: Encyclopedia II - Skygazing - The observation with a reflecting telescope

A refracting telescope is an instrument that is constituted of one or several lenses and that focuses the luminous rays toward one point called focus. The role of the eyepiece situated after the focus is to shape the picture so that it is visible for the eyes as well as to enlarge this one. A good refracting telescope is an instrument that one retains all his or her life, even after the acquisition of a bigger telescope. The refracting telescope, by its reduced opening (therefore little luminous), is especially adapted to the observat ...

See also:

Skygazing, Skygazing - Naked eye skygazing, Skygazing - Diurnal observation, Skygazing - Nocturnal observation, Skygazing - Binocular gazing, Skygazing - Choice of binoculars, Skygazing - Advice on observational techniques, Skygazing - Observations with a refracting telescope, Skygazing - Choice of the refracting telescope, Skygazing - Advice of usage, Skygazing - The observation with a reflecting telescope, Skygazing - Types of reflecting telescope

Read more here: » Skygazing: Encyclopedia II - Skygazing - Observations with a refracting telescope