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Telescope In Heng Ee Observatory
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 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
100inchHooker
1 (one, unit, unity) is a number representing a single or the only entity. 1 is also a numerical digit and represents a single unit of counting or measurement. For example, a line segment of ''unit length'' is a line segment of length 1. In conventions of sign where zero is considered neither positive nor negative, 1 is the first and smallest positive integer. It is also sometimes considered the first of the infinite sequence of natural numbers, followed by 2, although by other definitions 1 is the second natural number, following 0. The fundamental mathematical property of 1 is to be a multiplicative identity, meaning that any number multiplied by 1 equals the same number. Most if not all properties of 1 can be deduced from this. In advanced mathematics, a multiplicative identity is often denoted 1, even if it is not a number. 1 is by convention not considered a prime number; this was not universally accepted until the mid-20th century. Additionally, 1 is ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Spherical Aberration
In optics, spherical aberration (SA) is a type of optical aberration, aberration found in optical systems that have elements with spherical surfaces. Lens (optics), Lenses and curved mirrors are prime examples, because this shape is easier to manufacture. Light rays that strike a spherical surface off-centre are refraction, refracted or reflection (physics), reflected more or less than those that strike close to the centre. This deviation reduces the quality of images produced by optical systems. Overview A spherical lens has an Optical aberration#Aberration of elements, i.e. smallest objects at right angles to the axis, aplanatic point (i.e., no spherical aberration) only at a radius that equals the radius of the sphere divided by the index of refraction of the lens material. A typical value of refractive index for crown glass is 1.5 (see List of refractive indices, list), which indicates that only about 43% of the area (67% of diameter) of a spherical lens is useful. It is o ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Parabolic Reflector
A parabolic (or paraboloid or paraboloidal) reflector (or dish or mirror) is a reflective surface used to collect or project energy such as light, sound, or radio waves. Its shape is part of a circular paraboloid, that is, the surface generated by a parabola revolving around its axis. The parabolic reflector transforms an incoming plane wave travelling along the axis into a spherical wave converging toward the focus. Conversely, a spherical wave generated by a point source placed in the focus is reflected into a plane wave propagating as a collimated beam along the axis. Parabolic reflectors are used to collect energy from a distant source (for example sound waves or incoming star light). Since the principles of reflection are reversible, parabolic reflectors can also be used to collimate radiation from an isotropic source into a parallel beam. In optics, parabolic mirrors are used to gather light in reflecting telescopes and solar furnaces, and project a beam of light in flas ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Allen & Unwin
George Allen & Unwin was a British publishing company formed in 1911 when Sir Stanley Unwin purchased a controlling interest in George Allen & Co. It went on to become one of the leading publishers of the twentieth century and to establish an Australian subsidiary in 1976. In 1990, Allen & Unwin was sold to HarperCollins and the Australian branch was the subject of a management buy-out. George Allen & Unwin in the UK George Allen & Sons was established in 1871 by George Allen, with the backing of John Ruskin, becoming George Allen & Co. Ltd. in 1911 and then George Allen & Unwin in 1914 as a result of Stanley Unwin's purchase of a controlling interest. Unwin's son Rayner S. Unwin and nephew Philip helped run the company, which published the works of Bertrand Russell, Arthur Waley, Roald Dahl, Lancelot Hogben, and Thor Heyerdahl. It became well known as J. R. R. Tolkien's publisher, some time after publishing the popular children's fantasy novel ''The Hobbit'' in 1937, and its ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Objective (optics)
In optical engineering, the objective is the optical element that gathers light from the object being observed and focuses the light rays to produce a real image. Objectives can be a single lens or mirror, or combinations of several optical elements. They are used in microscopes, binoculars, telescopes, cameras, slide projectors, CD players and many other optical instruments. Objectives are also called object lenses, object glasses, or objective glasses. Microscope objectives The objective lens of a microscope is the one at the bottom near the sample. At its simplest, it is a very high-powered magnifying glass, with very short focal length. This is brought very close to the specimen being examined so that the light from the specimen comes to a focus inside the microscope tube. The objective itself is usually a cylinder containing one or more lenses that are typically made of glass; its function is to collect light from the sample. Magnification One of the most important prope ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Zacharias Janssen
Zacharias Janssen; also Zacharias Jansen or Sacharias Jansen; 1585 – pre-1632) was a Dutch spectacle-maker who lived most of his life in Middelburg. He is associated with the invention of the first optical telescope and/or the first truly compound microscope, but these claims (made 20 years after his death) may be fabrications put forward by his son. Biography Zacharias Janssen was born in The Hague. Local records seem to indicate he was born in 1585 although a date of birth as early as 1580 or as late as 1588 are also given. His parents were Hans MartensSource: a book by Huib J. Zuidervaart which is to be published in the spring of 2008. The in Middelburg has already been shown a first version of this book. (who may have had the occupation of a peddler) and Maeyken Meertens, both probably from Antwerp, Belgium. He grew up with his sister Sara in Middelburg, at the time the second most important city of the Netherlands. He was known as a "street seller" who was constantly ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Jacob Metius
Jacob (Jacobus; sometimes James) Metius (after 1571–1628) was a Dutch instrument-maker and a specialist in grinding lenses. He is primarily known for the patent application he made for an optical telescope in October 1608, a few weeks after Hans Lippershey submitted a patent for the same device. He was the brother of the geometer and astronomer Adriaan Metius. Biography Little is known of Jacob Metius other than he lived his life in Alkmaar. His father was Adriaan Anthonisz, a mathematician/map-maker/military engineer and Alkmaar burgomaster, and his brother was Adriaan Metius. Jacob's date of birth was some time after his brother's (1571). He died in Alkmaar, his death date usually given in sources as 1628 although some put it between 1624 and 1631. Invention of the telescope In October 1608, the States General discussed Jacob Metius's patent application for a device for "seeing faraway things as though nearby", consisting of a convex and concave lens in a tube, and the co ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hans Lipperhey
Hans Lipperhey (circa 1570 – buried 29 September 1619), also known as Johann Lippershey or Lippershey, was a German-Dutch spectacle-maker. He is commonly associated with the invention of the telescope, because he was the first one who tried to obtain a patent for it. It is, however, unclear if he was the first one to build a telescope. Biography Lipperhey was born in Wesel, now in western Germany, around 1570. He settled in Middelburg, the capital of the province of Zeeland, now in the Netherlands, in 1594, married the same year and became a citizen of Zeeland in 1602. During that time he became a master lens grinder and spectacle maker and established a shop. He remained in Middelburg until his death, in September 1619. Invention of the telescope Hans Lipperhey is known for the earliest written record of a refracting telescope, a patent he filed in 1608. His work with optical devices grew out of his work as a spectacle maker, an industry that had started in Venice and Florenc ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Galileu Galilei 1608-2008=400 Anos Do Telescópio - Panoramio
''Galileu'' is a List of science magazines, science magazine in Brazil, which was founded in 1991. The magazine is owned by Editora Globo. ''Galileu'' was first called "Globo Ciência" (in English language, English "Globo Science"). The current magazine is named after Galileo Galilei, or '' Galileu Galilei'', in Portuguese. It is a competitor of ''Superinteressante'', another science and technology magazine. In 1998, ''Globo Ciência'' published its 86th edition and, from then on, changed its name to ''Galileu''. The first issue's topics centered on robots. The headquarters of the magazine which is published on a monthly basis is in São Paulo. The magazine mostly features articles on technology, research, environment, health and culture. References External links Official website 1991 establishments in Brazil Magazines published in Brazil Globo magazines Grupo Globo subsidiaries Magazines established in 1991 Monthly magazines published in Brazil Popular science magazines P ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Romanized
Romanization or romanisation, in linguistics, is the conversion of text from a different writing system to the Roman (Latin) script, or a system for doing so. Methods of romanization include transliteration, for representing written text, and transcription, for representing the spoken word, and combinations of both. Transcription methods can be subdivided into ''phonemic transcription'', which records the phonemes or units of semantic meaning in speech, and more strict ''phonetic transcription'', which records speech sounds with precision. Methods There are many consistent or standardized romanization systems. They can be classified by their characteristics. A particular system’s characteristics may make it better-suited for various, sometimes contradictory applications, including document retrieval, linguistic analysis, easy readability, faithful representation of pronunciation. * Source, or donor language – A system may be tailored to romanize text from a particular lang ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ancient Greek
Ancient Greek includes the forms of the Greek language used in ancient Greece and the ancient world from around 1500 BC to 300 BC. It is often roughly divided into the following periods: Mycenaean Greek (), Dark Ages (), the Archaic period (), and the Classical period (). Ancient Greek was the language of Homer and of fifth-century Athenian historians, playwrights, and philosophers. It has contributed many words to English vocabulary and has been a standard subject of study in educational institutions of the Western world since the Renaissance. This article primarily contains information about the Epic and Classical periods of the language. From the Hellenistic period (), Ancient Greek was followed by Koine Greek, which is regarded as a separate historical stage, although its earliest form closely resembles Attic Greek and its latest form approaches Medieval Greek. There were several regional dialects of Ancient Greek, of which Attic Greek developed into Koine. Dia ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
