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Dobsonian
A Dobsonian telescope is an altazimuth-mounted Newtonian telescope design popularized by John Dobson in 1965 and credited with vastly increasing the size of telescopes available to amateur astronomers. Dobson's telescopes featured a simplified mechanical design that was easy to manufacture from readily available components to create a large, portable, low-cost telescope. The design is optimized for observing faint, deep-sky objects such as nebulae and galaxies. This type of observation requires a large objective diameter (i.e. light-gathering power) of relatively short focal length and portability for travel to less light-polluted locations. Dobsonians are intended to be what is commonly called a "light bucket" operating at low magnification, and therefore the design omits features found in other amateur telescopes such as equatorial tracking. Dobsonians are popular in the amateur telescope making community, where the design was pioneered and continues to evolve. A number of c ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
John Dobson (amateur Astronomer)
John Lowry Dobson (14 September 1915 – 15 January 2014) was an American amateur astronomer and is best known for the Dobsonian telescope, a portable, low-cost Newtonian reflector telescope. He was also known for his efforts to promote awareness of astronomy (and his unorthodox views of physical cosmology) through public lectures including his performances of " sidewalk astronomy". Dobson was also the co-founder of the amateur astronomical group, the San Francisco Sidewalk Astronomers. Biography Dobson was born to Methodist missionary parents in China, but moved with his family back to the U.S. as a young child. He was a “belligerent atheist” as a young man. After earning a masters in chemistry, he encountered a teacher of a Vedanta monastic order, which seeks to integrate Veda-based religious precepts with rational inquiry, and joined the order, where he served as a Vedantan monk for 23 years. After leaving the order (in part because the time he surreptitiously de ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Altazimuth Mount
An altazimuth mount or alt-azimuth mount is a simple two-axis mount for supporting and rotating an instrument about two perpendicular axes – one vertical and the other horizontal. Rotation about the vertical axis varies the azimuth (compass bearing) of the pointing direction of the instrument. Rotation about the horizontal axis varies the altitude angle (angle of elevation) of the pointing direction. These mounts are used, for example, with telescopes, cameras, radio antennas, heliostat mirrors, solar panels, and guns and similar weapons. Several names are given to this kind of mount, including altitude-azimuth, azimuth-elevation and various abbreviations thereof. A gun turret is essentially an alt-azimuth mount for a gun, and a standard camera tripod is an alt-azimuth mount as well. Astronomical telescope altazimuth mounts When used as an astronomical telescope mount, the biggest advantage of an alt-azimuth mount is the simplicity of its mechanical design. The primary disadv ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Teflon
Polytetrafluoroethylene (PTFE) is a synthetic fluoropolymer of tetrafluoroethylene that has numerous applications. It is one of the best-known and widely applied PFAS. The commonly known brand name of PTFE-based composition is Teflon by Chemours, a spin-off from DuPont, which originally discovered the compound in 1938. Polytetrafluoroethylene is a fluorocarbon solid, as it is a high-molecular-weight polymer consisting wholly of carbon and fluorine. PTFE is hydrophobic: neither water nor water-containing substances wet PTFE, as fluorocarbons exhibit only small London dispersion forces due to the low electric polarizability of fluorine. PTFE has one of the lowest coefficients of friction of any solid. Polytetrafluoroethylene is used as a non-stick coating for pans and other cookware. It is non-reactive, partly because of the strength of carbon–fluorine bonds, so it is often used in containers and pipework for reactive and corrosive chemicals. Where used as a lubricant, PT ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sidewalk Astronomy
Sidewalk astronomy or street corner astronomy refers to the activity of setting up a telescope in an urban place on a for-profit or non-profit basis as entertainment and/or for public education. Overview Examples of people setting up telescopes on urban streets for public astronomical viewing go back well into the 19th century and maybe even further. Sidewalk astronomers and their telescopes have been a common sight in most big cities. There are many examples in the past such as Frank Manning in New Orleans as early as 1930 and Mr Grosser in Los Angeles in the 1870s, who not only set up a telescope but also an illuminated microscope. Some sidewalk "pitch men" charged the public to view astronomical objects through their telescope but other astronomers allow people to view for free. In more recent years sidewalk astronomy has come to be more associated with altruistic individuals or groups offering views of the nighttime sky as a free public educational service." Because the sidew ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Deep Sky Object
A deep-sky object (DSO) is any astronomical object that is not an individual star or Solar System object (such as Sun, Moon, planet, comet, etc.). The classification is used for the most part by amateur astronomers to denote visually observed faint naked eye and telescopic objects such as star clusters, nebulae and galaxies. This distinction is practical and technical, implying a variety of instruments and techniques appropriate to observation, and does not distinguish the nature of the object itself. Origins and classification Classifying non-stellar astronomical objects began soon after the invention of the telescope. One of the earliest comprehensive lists was Charles Messier's 1774 Messier catalog, which included 103 "''nebulae''" and other faint fuzzy objects he considered a nuisance since they could be mistaken for comets, the objects he was actually searching for. As telescopes improved these faint nebulae would be broken into more descriptive scientific classifications s ... [...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] |
Trunnions
A trunnion (from Old French "''trognon''", trunk) is a cylindrical protrusion used as a mounting or pivoting point. First associated with cannons, they are an important military development. Alternatively, a trunnion is a shaft that positions and supports a tilting plate. This is a misnomer, as in reality it is a cradle for the true trunnion. In mechanical engineering (see the trunnion bearing section below), it is one part of a rotating joint where a shaft (the trunnion) is inserted into (and turns inside) a full or partial cylinder. Medieval history In a cannon, the trunnions are two projections cast just forward of the center of mass of the cannon and fixed to a two-wheeled movable gun carriage. As they allowed the muzzle to be raised and lowered easily, the integral casting of trunnions is seen by military historians as one of the most important advances in early field artillery. With the creation of larger and more powerful siege guns in the early 15th century, a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Deep-sky Object
A deep-sky object (DSO) is any astronomical object that is not an individual star or Solar System object (such as Sun, Moon, planet, comet, etc.). The classification is used for the most part by amateur astronomers to denote visually observed faint naked eye and telescopic objects such as star clusters, nebulae and galaxies. This distinction is practical and technical, implying a variety of instruments and techniques appropriate to observation, and does not distinguish the nature of the object itself. Origins and classification Classifying non-stellar astronomical objects began soon after the invention of the telescope. One of the earliest comprehensive lists was Charles Messier's 1774 Messier catalog, which included 103 "''nebulae''" and other faint fuzzy objects he considered a nuisance since they could be mistaken for comets, the objects he was actually searching for. As telescopes improved these faint nebulae would be broken into more descriptive scientific classifications ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Deep-sky Object
A deep-sky object (DSO) is any astronomical object that is not an individual star or Solar System object (such as Sun, Moon, planet, comet, etc.). The classification is used for the most part by amateur astronomers to denote visually observed faint naked eye and telescopic objects such as star clusters, nebulae and galaxies. This distinction is practical and technical, implying a variety of instruments and techniques appropriate to observation, and does not distinguish the nature of the object itself. Origins and classification Classifying non-stellar astronomical objects began soon after the invention of the telescope. One of the earliest comprehensive lists was Charles Messier's 1774 Messier catalog, which included 103 "''nebulae''" and other faint fuzzy objects he considered a nuisance since they could be mistaken for comets, the objects he was actually searching for. As telescopes improved these faint nebulae would be broken into more descriptive scientific classifications ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Amateur Astronomy
Amateur astronomy is a hobby where participants enjoy observing or imaging celestial objects in the sky using the unaided eye, binoculars, or telescopes. Even though scientific research may not be their primary goal, some amateur astronomers make contributions in doing citizen science, such as by monitoring variable stars, double stars, sunspots, or occultations of stars by the Moon or asteroids, or by discovering transient astronomical events, such as comets, galactic novae or supernovae in other galaxies. Amateur astronomers do not use the field of astronomy as their primary source of income or support, and usually have no professional degree in astrophysics or advanced academic training in the subject. Most amateurs are hobbyists, while others have a high degree of experience in astronomy and may often assist and work alongside professional astronomers. Many astronomers have studied the sky throughout history in an amateur framework; however, since the beginning of the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Formica (plastic)
Formica Laminate is a laminated composite material invented at the Westinghouse Electric Corporation in the United States in 1912. Originally used to replace mica in electrical applications, it has since been manufactured for multiple applications. It has been produced by Formica Group manufacturing sites across the globe since. Formica Group are best known for the company's classic product: a heat-resistant, wipe-clean laminate of paper or textile with melamine resin. Formica Group, a division of the Dutch company Broadview Holdings, consists of Formica Canada, Inc., Formica Corporation, Formica de Mexico S.A. de C.V., Formica IKI Oy, Formica Limited, Formica S.A., Formica S.A.S., Formica Taiwan Corporation, Formica (Thailand) Co., Ltd., Formica (Asia) Ltd., and others. Etymology The mineral mica was commonly used at that time for electrical insulation. Because the new product acted as a substitute "for mica", Faber used the name ''Formica'' as a trademark. The word alread ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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