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Schmidt–Väisälä Camera
The Schmidt–Väisälä camera is a type of astronomical telescope intended for wide-field (5 to 10 degrees of arc) photographic work. It was designed by Finnish physicist Yrjö Väisälä. Invention and design Professor Väisälä originally designed an "astronomical camera" similar to Bernhard Schmidt's Schmidt camera, but the design was unpublished. Väisälä did mention it in a lecture notes in 1924 with a footnote: "problematic spherical focal plane". Once Väisälä saw Schmidt's publication, he promptly went ahead and solved the field-flattening problem in Schmidt's design by placing a doubly convex lens slightly in front of the film holder. This resulting system is known as a ''Schmidt–Väisälä camera'' or sometimes as ''Väisälä camera''. This flat-field correction is not perfect, as images suffer from chromatic aberration with different colors ending up at slightly different places. However the approach has attracted interest for modern electronic image se ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Astronomical Telescope
A telescope is a device used to observe distant objects by their emission, absorption, or reflection of electromagnetic radiation. Originally meaning only an optical instrument using lenses, curved mirrors, or a combination of both to observe distant objects, the word ''telescope'' now refers to a wide range of instruments capable of detecting different regions of the electromagnetic spectrum, and in some cases other types of detectors. The first known practical telescopes were refracting telescopes with glass lenses and were invented in the Netherlands at the beginning of the 17th century. They were used for both terrestrial applications and astronomy. The reflecting telescope, which uses mirrors to collect and focus light, was invented within a few decades of the first refracting telescope. In the 20th century, many new types of telescopes were invented, including radio telescopes in the 1930s and infrared telescopes in the 1960s. Etymology The word ''telescope'' was ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Blink Comparator
A blink comparator is a viewing apparatus formerly used by astronomers to find differences between two photographs of the night sky. It permits rapid switching from viewing one photograph to viewing the other, "blinking" back and forth between the two images taken of the same area of the sky at different times. This allows the user to more easily spot objects in the night sky that have changed position or brightness. It was also sometimes known as a blink microscope. It was invented in 1904 by physicist Carl Pulfrich at Carl Zeiss AG, then constituted as Carl-Zeiss-Stiftung. In photographs taken a few days apart, rapidly moving objects such as asteroids and comets would stand out, because they would appear to be jumping back and forth between two positions, while all the distant stars remained stationary. Photographs taken at longer intervals could be used to detect stars with large proper motion, or variable stars, or to distinguish binary stars from optical doubles. The most n ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Reflecting Telescope
A reflecting telescope (also called a reflector) is a telescope that uses a single or a combination of curved mirrors that reflect light and form an image. The reflecting telescope was invented in the 17th century by Isaac Newton as an alternative to the refracting telescope which, at that time, was a design that suffered from severe chromatic aberration. Although reflecting telescopes produce other types of optical aberrations, it is a design that allows for very large diameter objectives. Almost all of the major telescopes used in astronomy research are reflectors. Many variant forms are in use and some employ extra optical elements to improve image quality or place the image in a mechanically advantageous position. Since reflecting telescopes use mirrors, the design is sometimes referred to as a catoptrics, catoptric telescope. From the time of Newton to the 1800s, the mirror itself was made of metal usually speculum metal. This type included Newton's first designs and eve ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Optical Telescope
An optical telescope is a telescope that gathers and focuses light mainly from the visible part of the electromagnetic spectrum, to create a magnified image for direct visual inspection, to make a photograph, or to collect data through electronic image sensors. There are three primary types of optical telescope: * Refracting telescopes, which use lenses and less commonly also prisms (dioptrics) * Reflecting telescopes, which use mirrors (catoptrics) * Catadioptric telescopes, which combine lenses and mirrors An optical telescope's ability to resolve small details is directly related to the diameter (or aperture) of its objective (the primary lens or mirror that collects and focuses the light), and its light-gathering power is related to the area of the objective. The larger the objective, the more light the telescope collects and the finer detail it resolves. People use optical telescopes (including monoculars and binoculars) for outdoor activities such as observational as ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
List Of Telescope Types
The following are lists of devices categorized as types of telescopes or devices associated with telescopes. They are broken into major classifications with many variations due to professional, amateur, and commercial sub-types. Telescopes can be classified by optical design or mechanical design/construction. Telescopes can also be classified by where they are placed, such as space telescopes. One major determining factor is type of light, or particle being observed including devices referred to as "telescopes" that do not form an image or use optics. Some telescopes are classified by the task they perform; for example Solar telescopes are all designs that look at the Sun, Dobsonian telescopes are designed to be low cost and portable, Aerial telescopes overcame the optical shortcomings of 17th-century objective lenses, etc. List of optical telescope types Optical telescopes can be classified by three primary optical designs (refractor, reflector, or catadioptric), by sub-designs o ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Astronomical Seeing
In astronomy, seeing is the degradation of the image of an astronomical object due to turbulence in the atmosphere of Earth that may become visible as blurring, twinkling or variable distortion. The origin of this effect are rapidly changing variations of the optical refractive index along the light path of the object. Seeing is a major limitation to the angular resolution in astronomical observations with telescopes that would otherwise be limited through diffraction by the size of the telescope aperture. Today, many large scientific ground-based optical telescopes include adaptive optics to overcome seeing. The strength of seeing is often characterized by the angular diameter of the long-exposure image of a star (''seeing disk'') or by the Fried parameter ''r''0. The diameter of the seeing disk is the full width at half maximum of its optical intensity. An exposure time of several tens of milliseconds can be considered ''long'' in this context. The Fried parameter describe ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pluto
Pluto (minor-planet designation: 134340 Pluto) is a dwarf planet in the Kuiper belt, a ring of trans-Neptunian object, bodies beyond the orbit of Neptune. It is the ninth-largest and tenth-most-massive known object to directly orbit the Sun. It is the largest known trans-Neptunian object by volume, by a small margin, but is slightly less massive than Eris (dwarf planet), Eris. Like other Kuiper belt objects, Pluto is made primarily of ice and rock and is much smaller than the inner planets. Compared to Moon, Earth's moon, Pluto has only one sixth its mass and one third its volume. Pluto has a moderately orbital eccentricity, eccentric and inclined orbit, ranging from from the Sun. Light from the Sun takes 5.5 hours to reach Pluto at its average distance (). Pluto's eccentric orbit periodically brings it closer to the Sun than Neptune, but a stable orbital resonance prevents them from colliding. Pluto has moons of Pluto, five known moons: Charon (moon), Charon, the larg ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Kevola Observatory
The Kevola Observatory is located in Kevola in Paimio in South-Western Finland, some 35 km east from the city of Turku. The observatory is currently owned by ''Turun Ursa ry'', a local astronomical association operating in Turku area. The buildings of the observatory include an observatory dome, a zenith observatory, and a house for recording observations. Kevola Observatory has code 064 in the IAU/MPC observatory list. The main-belt asteroid 1540 Kevola was named after the observatory. History The observatory was built in 1963 by ''Tähtitieteellis-optillinen seura'' (Astronomy-Optical Society) on a small hill on lands of the home farm of Hilkka Rantaseppä-Helenius. She worked at the time as an observer at Tuorla Observatory of University of Turku. The association was founded by Yrjö Väisälä, Liisi Oterma, Hilkka Rantaseppä-Helenius, and other astronomers working at University of Turku. The association was terminated in 1983. In 1986 the observatory buildin ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Finland
Finland ( fi, Suomi ; sv, Finland ), officially the Republic of Finland (; ), is a Nordic country in Northern Europe. It shares land borders with Sweden to the northwest, Norway to the north, and Russia to the east, with the Gulf of Bothnia to the west and the Gulf of Finland across Estonia to the south. Finland covers an area of with a population of 5.6 million. Helsinki is the capital and largest city, forming a larger metropolitan area with the neighbouring cities of Espoo, Kauniainen, and Vantaa. The vast majority of the population are ethnic Finns. Finnish, alongside Swedish, are the official languages. Swedish is the native language of 5.2% of the population. Finland's climate varies from humid continental in the south to the boreal in the north. The land cover is primarily a boreal forest biome, with more than 180,000 recorded lakes. Finland was first inhabited around 9000 BC after the Last Glacial Period. The Stone Age introduced several differ ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Turku
Turku ( ; ; sv, Åbo, ) is a city and former capital on the southwest coast of Finland at the mouth of the Aura River, in the region of Finland Proper (''Varsinais-Suomi'') and the former Turku and Pori Province (''Turun ja Porin lääni''; 1634–1997). The region was originally called Suomi (Finland), which later became the name for the whole country. As of 31 March 2021, the population of Turku was 194,244 making it the sixth largest city in Finland after Helsinki, Espoo, Tampere, Vantaa and Oulu. There were 281,108 inhabitants living in the Turku Central Locality, ranking it as the third largest urban area in Finland after the Capital Region area and Tampere Central Locality. The city is officially bilingual as percent of its population identify Swedish as a mother-tongue. It is unknown when Turku gained city rights. The Pope Gregory IX first mentioned the town ''Aboa'' in his ''Bulla'' in 1229 and the year is now used as the foundation year of Turku. Turku ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Iso-Heikkilä Observatory
Iso-Heikkilä Observatory ( fi, Iso-Heikkilän tähtitorni, sv, Storheikkilä observatorium) is an amateur astronomical observatory used by a local amateur astronomical association, Turun Ursa ry in the Iso-Heikkilä district of Turku, Finland. Referred to as Turku Observatory () by the Minor Planet Center, it was previously operated by the University of Turku from 1937 to 1972, and is the observatory where several Finnish discoverers of minor planets made their observations. History The observatory was originally owned by the department of astronomy of the University of Turku. It was built in 1935 and 1936, and technically designed by physics and astronomy professor Yrjö Väisälä. Väisälä's research team discovered a total of 807 minor planets and 7 comets at the observatory. Väisälä also contributed significantly to research in the areas of optics and surveying. As the city expanded and a steel factory was built under a kilometer away from the observatory, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Equatorial Mount
An equatorial mount is a mount for instruments that compensates for Earth's rotation by having one rotational axis, the polar axis, parallel to the Earth's axis of rotation. This type of mount is used for astronomical telescopes and cameras. The advantage of an equatorial mount lies in its ability to allow the instrument attached to it to stay fixed on any celestial object with diurnal motion by driving one axis at a constant speed. Such an arrangement is called a sidereal or clock drive. Equatorial mounts achieve this by aligning their rotational axis with the Earth, a process known as polar alignment. Astronomical telescope mounts In astronomical telescope mounts, the equatorial axis (the '' right ascension'') is paired with a second perpendicular axis of motion (known as the '' declination''). The equatorial axis of the mount is often equipped with a motorized "''clock drive''", that rotates that axis one revolution every 23 hours and 56 minutes in exact sync with the appar ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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