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Meudon Great Refractor
Meudon Great Refractor (also known as the ''Grande Lunette'') is a double telescope with lenses (83 cm + 62 cm), in Meudon, France. It is a twin refracting telescope built in 1891, with one visual and one photographic, on a single square-tube together on an equatorial mount, inside a dome. The Refractor was built for the Meudon Observatory, and is the largest double doublet (twin achromat) refracting telescope in Europe, but about the same size as several telescopes in this period, when this style of telescope was popular. Other large telescopes of a similar type include the James Lick telescope (91.4), Potsdam Great Refractor (80+50 cm), and the Greenwich 28 inch refractor (71.1 cm). Institutionally it was part of the Meudon Observatory, which later became integrated with the Paris observatory. The Great Refractor was used for research well into the 1980s, after nearly a century of use. In the 21st century it was renovated and re-opened for public outreach ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Grande Coupole De Meudon
Grande means "large" or "great" in many of the Romance languages. It may also refer to: Places * Grande, Germany, a municipality in Germany *Grande Communications, a telecommunications firm based in Texas *Grande-Rivière (other) *Arroio Grande (other) * Boca grande (other) *Campo Grande (other) *El Grande, a German-style board game *Loma Grande (other) *Lucida Grande, a humanist sans-serif typeface *María Grande, a village and municipality in Entre Ríos Province in northeastern Argentina *Mojón Grande, a village and municipality in Misiones Province in northeastern Argentina *Playa Grande (other) * Ribeira Grande (other) *Rio Grande (other) * Salto Grande (other) *Valle Grande (other) * Várzea Grande (other) *Villa Grande (other) *Casa Grande Ruins National Monument *Casas Grandes *Mesa Grande *Pueblo Grande de Nevada *Pueblo Grande Ruin and Irrigation Sites *Campina Gr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Film Emulsion
Photographic emulsion is a light-sensitive colloid used in film-based photography. Most commonly, in silver-gelatin photography, it consists of silver halide crystals dispersed in gelatin. The emulsion is usually coated onto a substrate of glass, films (of cellulose nitrate, cellulose acetate or polyester), paper, or fabric. Photographic emulsion is not a true emulsion, but a suspension of solid particles (silver halide) in a fluid (gelatin in solution). However, the word ''emulsion'' is customarily used in a photographic context. Gelatin or gum arabic layers sensitized with dichromate used in the dichromated colloid processes carbon and gum bichromate are sometimes called ''emulsions''. Some processes do not have emulsions, such as platinum, cyanotype, salted paper, or kallitype. Components Photographic emulsion is a fine suspension of insoluble light-sensitive crystals in a colloid sol, usually consisting of gelatin. The light-sensitive component is one or a mixture of s ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ministry Of Education (France)
An education ministry is a national or subnational government agency politically responsible for education. Various other names are commonly used to identify such agencies, such as Ministry of Education, Department of Education, and Ministry of Public Education, and the head of such an agency may be a minister of education or secretary of education. Such agencies typically address educational concerns such as the quality of schools or standardization of curriculum. The first such ministry ever is considered to be the Commission of National Education ( pl, Komisja Edukacji Narodowej, lt, Edukacinė komisija), founded in 1773 in the Polish–Lithuanian Commonwealth. Following is a list of education ministries by country: Africa * Ministry of National Education (Algeria) * Ministry of Education (Egypt) * Ministry of Education (Ethiopia) * Ministry of Education (Ghana) * Ministry of Education (Kenya) * Ministry of Education (Namibia) * Nigeria: :* Federal Ministry of Education (N ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Moon
The Moon is Earth's only natural satellite. It is the fifth largest satellite in the Solar System and the largest and most massive relative to its parent planet, with a diameter about one-quarter that of Earth (comparable to the width of Australia). The Moon is a planetary-mass object with a differentiated rocky body, making it a satellite planet under the geophysical definitions of the term and larger than all known dwarf planets of the Solar System. It lacks any significant atmosphere, hydrosphere, or magnetic field. Its surface gravity is about one-sixth of Earth's at , with Jupiter's moon Io being the only satellite in the Solar System known to have a higher surface gravity and density. The Moon orbits Earth at an average distance of , or about 30 times Earth's diameter. Its gravitational influence is the main driver of Earth's tides and very slowly lengthens Earth's day. The Moon's orbit around Earth has a sidereal period of 27.3 days. During each synodic period ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Polaris
Polaris is a star in the northern circumpolar constellation of Ursa Minor. It is designated α Ursae Minoris ( Latinized to ''Alpha Ursae Minoris'') and is commonly called the North Star or Pole Star. With an apparent magnitude that fluctuates around 1.98, it is the brightest star in the constellation and is readily visible to the naked eye at night. The position of the star lies less than 1° away from the north celestial pole, making it the current northern pole star. The stable position of the star in the Northern Sky makes it useful for navigation. As the closest Cepheid variable its distance is used as part of the cosmic distance ladder. The revised ''Hipparcos'' stellar parallax gives a distance to Polaris of about , while the successor mission ''Gaia'' gives a distance of about . Calculations by other methods vary widely. Although appearing to the naked eye as a single point of light, Polaris is a triple star system, composed of the primary, a yellow super ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Grande Lunette De L'Observatoire De Meudon
Grande means "large" or "great" in many of the Romance languages. It may also refer to: Places *Grande, Germany, a municipality in Germany *Grande Communications, a telecommunications firm based in Texas *Grande-Rivière (other) *Arroio Grande (other) * Boca grande (other) *Campo Grande (other) *El Grande, a German-style board game *Loma Grande (other) *Lucida Grande, a humanist sans-serif typeface *María Grande, a village and municipality in Entre Ríos Province in northeastern Argentina *Mojón Grande, a village and municipality in Misiones Province in northeastern Argentina *Playa Grande (other) * Ribeira Grande (other) *Rio Grande (other) * Salto Grande (other) *Valle Grande (other) * Várzea Grande (other) *Villa Grande (other) *Casa Grande Ruins National Monument *Casas Grandes *Mesa Grande *Pueblo Grande de Nevada *Pueblo Grande Ruin and Irrigation Sites *Campina Gra ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Bernard Lyot
Bernard Ferdinand Lyot (27 February 1897 in Paris – 2 April 1952 in Cairo) was a French astronomer. Biography An avid reader of the works of Camille Flammarion, he became a member of the Société Astronomique de France in 1915 and made his first observations using the society's telescope on rue Serpente in Paris. He soon acquired a telescope and soon upgraded to a . From graduation in 1918 until 1929, he worked as a demonstrator at the École Polytechnique and studied engineering, physics, and chemistry at the University of Paris. From 1920 until his death he worked for the Meudon Observatory, where in 1930 he earned the title of ''Joint Astronomer of the Observatory''. After gaining the title, he earned a reputation of being an expert of polarized and monochromatic light. Throughout the 1930s, he labored to perfect the coronagraph, which he invented to observe the corona without having to wait for a solar eclipse. In 1938, he showed a movie of the corona in action to th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Polarization Of Light
Polarization (also polarisation) is a property applying to transverse waves that specifies the geometrical orientation of the oscillations. In a transverse wave, the direction of the oscillation is perpendicular to the direction of motion of the wave. A simple example of a polarized transverse wave is vibrations traveling along a taut string ''(see image)''; for example, in a musical instrument like a guitar string. Depending on how the string is plucked, the vibrations can be in a vertical direction, horizontal direction, or at any angle perpendicular to the string. In contrast, in longitudinal waves, such as sound waves in a liquid or gas, the displacement of the particles in the oscillation is always in the direction of propagation, so these waves do not exhibit polarization. Transverse waves that exhibit polarization include electromagnetic waves such as light and radio waves, gravitational waves, and transverse sound waves (shear waves) in solids. An electromagnetic wave ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Yerkes Observatory
Yerkes Observatory ( ) is an astronomical observatory located in Williams Bay, Wisconsin, United States. The observatory was operated by the University of Chicago Department of Astronomy and Astrophysics from its founding in 1897 to 2018. Ownership was transferred to the non-profit Yerkes Future Foundation (YFF) in May 2020, which began restoration and renovation of the historic building and grounds. Re-opening for public tours and programming began May 27, 2022. The observatory, often called "the birthplace of modern astrophysics," was founded in 1892 by astronomer George Ellery Hale and financed by businessman Charles T. Yerkes. It represented a shift in the thinking about observatories, from their being mere housing for telescopes and observers, to the early-20th-century concept of observation equipment integrated with laboratory space for physics and chemistry analysis. The observatory's main dome houses a doublet lens refracting telescope, the largest refractor ever ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lick Observatory
The Lick Observatory is an astronomical observatory owned and operated by the University of California. It is on the summit of Mount Hamilton, in the Diablo Range just east of San Jose, California, United States. The observatory is managed by the University of California Observatories, with headquarters on the University of California, Santa Cruz campus, where its scientific staff moved in the mid-1960s. It is named after James Lick. The first new moon of Jupiter to be identified since the time of Galileo was discovered at this observatory; Amalthea, the planet's fifth moon, was discovered at this observatory in 1892. Early history Lick Observatory is the world's first permanently occupied mountain-top observatory. The observatory, in a Classical Revival style structure, was constructed between 1876 and 1887, from a bequest from James Lick of $700,000, . Lick, originally a carpenter and piano maker, had arrived from Peru in San Francisco, California, in late 1847; after ac ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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