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Brukkaros Solar Observatory
The Brukkaros Solar Observatory was a solar observatory installed on Brukkaros Mountain in the ǁKaras Region of Namibia. It was financed and operated by a cooperation of the American National Geographic Society and the Smithsonian Institution, and it was operational between 1926 and 1931. Installation In 1926 the National Geographic Society, in cooperation with the Smithsonian Institution, financed an expedition to South-West Africa (now Namibia) to measure the intensity of solar radiation. The project was managed by the Smithsonian Astrophysical Observatory, which from 1906 to 1944 was directed by Dr Charles Greeley Abbot. During these years the observatory was dedicated mainly to the study of possible variations in the solar constant and the effects of such variations on the weather. For this purpose solar observatories had been established in Chile and Arizona. To check and confirm the small variations in the solar constant found at these two sites, Abbot received a grant from ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Solar Observatory
A solar observatory is an observatory that specializes in monitoring the Sun. As such, they usually have one or more solar telescopes. The Einstein Tower was a solar observatory in the Albert Einstein Science Park in Potsdam, Germany. Solar observatories study phenomena associated with the Sun. The Sun, being the closest star to earth, allows a unique chance to study stellar physics with high-resolution. It was, until the 1990s, the only star whose surface had been resolved. General topics that interest a solar astronomer are its 11-year periodicity (i.e., the Solar Cycle), sunspots, magnetic field activity (see solar dynamo), solar flares, coronal mass ejections, differential rotation, and plasma physics. Some examples * Huairou Solar Observing Station * Solar observatories in space * National Solar Observatory See also * Coronagraph * Heliometer * Helioscope * List of solar telescopes * Spectroheliograph * Spectrohelioscope * Solar astronomy * Solar tower (astronomy) A ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Keetmanshoop
Keetmanshoop is a city in the ǁKaras Region of southern Namibia, lying on the Trans-Namib Railway from Windhoek to Upington in South Africa. It is named after Johann Keetman, a German industrialist and benefactor of the city. History Before the colonial era, the settlement was known as ''ǂNuǂgoaes'' or ''Swartmodder'', both of which mean "Black Marsh" and indicated the presence of a spring in the area. The first white settler, Guilliam Visagie, arrived here in 1785. When in February 1850 the Kharoǃoan clan ( Keetmanshoop Nama) split from the Red Nation, the main subtribe of the Nama people, they settled permanently here. In 1860 the Rhenish Missionary Society founded a mission there to christianise the local Nama. The first missionary, Johann Georg Schröder, arrived in Keetmanshoop on April 14, 1866, which is now marked as the founding date of Keetmanshoop. The mission station was named after the German trader and director of the Rhenish Missionary Society, , who supp ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Alloy
An alloy is a mixture of chemical elements of which at least one is a metal. Unlike chemical compounds with metallic bases, an alloy will retain all the properties of a metal in the resulting material, such as electrical conductivity, ductility, opacity (optics), opacity, and lustre (mineralogy), luster, but may have properties that differ from those of the pure metals, such as increased strength or hardness. In some cases, an alloy may reduce the overall cost of the material while preserving important properties. In other cases, the mixture imparts synergistic properties to the constituent metal elements such as corrosion resistance or mechanical strength. Alloys are defined by a metallic bonding character. The alloy constituents are usually measured by mass percentage for practical applications, and in Atomic ratio, atomic fraction for basic science studies. Alloys are usually classified as substitutional or interstitial alloys, depending on the atomic arrangement that forms the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cobalt
Cobalt is a chemical element with the symbol Co and atomic number 27. As with nickel, cobalt is found in the Earth's crust only in a chemically combined form, save for small deposits found in alloys of natural meteoric iron. The free element, produced by reductive smelting, is a hard, lustrous, silver-gray metal. Cobalt-based blue pigments ( cobalt blue) have been used since ancient times for jewelry and paints, and to impart a distinctive blue tint to glass, but the color was for a long time thought to be due to the known metal bismuth. Miners had long used the name ''kobold ore'' (German for ''goblin ore'') for some of the blue-pigment-producing minerals; they were so named because they were poor in known metals, and gave poisonous arsenic-containing fumes when smelted. In 1735, such ores were found to be reducible to a new metal (the first discovered since ancient times), and this was ultimately named for the ''kobold''. Today, some cobalt is produced specifically from one of ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Stellite
Stellite is a range of cobalt-chromium alloys designed for wear resistance. The alloys may also contain tungsten or molybdenum and a small, but important, amount of carbon. History Stellite is a trademarked name of Kennametal Inc. Prior to that it was owned by Union Carbide, Stellite Division. Invented by Elwood Haynes in the early 1900s as a material for making cutlery that wouldn't stain or require constant cleaning. Composition Stellite alloys are a range of cobalt-based alloys, with significant proportions of chromium (up to 33%) and tungsten (up to 18%). Some of the alloys also contain nickel or molybdenum. Most of them are fairly high carbon content when compared to carbon steels, though they contain less than 3% iron, and in the stellite alloys the carbon is primarily associated with the chromium to form hard chromium carbide particles which are dispersed in the cobalt-based matrix. Properties Stellite is a family of completely non-magnetic and corrosion-resistant co ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Clockwork
Clockwork refers to the inner workings of either mechanical devices called clocks and watches (where it is also called the movement) or other mechanisms that work similarly, using a series of gears driven by a spring or weight. A clockwork mechanism is often powered by a clockwork motor, description of the clockwork motor in an antique phonograph consisting of a mainspring, a spiral torsion spring of metal ribbon. Energy is stored in the mainspring manually by ''winding it up'', turning a key attached to a ratchet which twists the mainspring tighter. Then the force of the mainspring turns the clockwork gears, until the stored energy is used up. The adjectives ''wind-up'' and ''spring-powered'' refer to mainspring-powered clockwork devices, which include clocks and watches, kitchen timers, music boxes, and wind-up toys. History The earliest known example of a clockwork mechanism is the Antikythera mechanism, a first-century BC geared analogue computer, somewhat astrolabe-li ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mirror
A mirror or looking glass is an object that Reflection (physics), reflects an image. Light that bounces off a mirror will show an image of whatever is in front of it, when focused through the lens of the eye or a camera. Mirrors reverse the direction of the image in an equal yet opposite angle from which the light shines upon it. This allows the viewer to see themselves or objects behind them, or even objects that are at an angle from them but out of their field of view, such as around a corner. Natural mirrors have existed since prehistoric times, such as the surface of water, but people have been manufacturing mirrors out of a variety of materials for thousands of years, like stone, metals, and glass. In modern mirrors, metals like silver or aluminium are often used due to their high reflectivity, applied as a thin coating on glass because of its naturally smooth and very Hardness (materials science), hard surface. A mirror is a Wave (physics), wave reflector. Light consis ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Coelostat
A solar telescope is a special purpose telescope used to observe the Sun. Solar telescopes usually detect light with wavelengths in, or not far outside, the visible spectrum. Obsolete names for Sun telescopes include heliograph and photoheliograph. Professional solar telescopes Solar telescopes need optics large enough to achieve the best possible diffraction limit but less so for the associated light-collecting power of other astronomical telescopes. However, recently newer narrower filters and higher framerates have also driven solar telescopes towards photon-starved operations. Both the Daniel K. Inouye Solar Telescope as well as the proposed European Solar Telescope (EST) have larger apertures not only to increase the resolution, but also to increase the light-collecting power. Because solar telescopes operate during the day, seeing is generally worse than for night-time telescopes, because the ground around the telescope is heated which causes turbulence and degrades the res ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pyranometer
A pyranometer is a type of actinometer used for measuring solar irradiance on a planar surface and it is designed to measure the solar radiation flux density (W/m2) from the hemisphere above within a wavelength range 0.3 μm to 3 μm. The name pyranometer stems from the Greek words ''πῦρ'' (''pyr''), meaning "fire", and ''ἄνω'' (''ano''), meaning "above, sky". A typical pyranometer does not require any power to operate. However, recent technical development includes use of electronics in pyranometers, which do require (low) external power. Explanation The solar radiation spectrum that reaches earth's surface extends its wavelength approximately from 300 nm to 2800 nm. Depending on the type of pyranometer used, irradiance measurements with different degrees of spectral sensitivity will be obtained. To make a measurement of irradiance, it is required by definition that the response to "beam" radiation varies with the cosine of the angle of incidence. This ensure ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Theodolite
A theodolite () is a precision optical instrument for measuring angles between designated visible points in the horizontal and vertical planes. The traditional use has been for land surveying, but it is also used extensively for building and infrastructure construction, and some specialized applications such as meteorology and rocket launching. It consists of a moveable telescope mounted so it can rotate around horizontal and vertical axes and provide angular readouts. These indicate the orientation of the telescope, and are used to relate the first point sighted through the telescope to subsequent sightings of other points from the same theodolite position. These angles can be measured with accuracies down to microradians or seconds of arc. From these readings a plan can be drawn, or objects can be positioned in accordance with an existing plan. The modern theodolite has evolved into what is known as a total station where angles and distances are measured electronically, and ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pendulum
A pendulum is a weight suspended from a pivot so that it can swing freely. When a pendulum is displaced sideways from its resting, equilibrium position, it is subject to a restoring force due to gravity that will accelerate it back toward the equilibrium position. When released, the restoring force acting on the pendulum's mass causes it to oscillate about the equilibrium position, swinging back and forth. The time for one complete cycle, a left swing and a right swing, is called the period. The period depends on the length of the pendulum and also to a slight degree on the amplitude, the width of the pendulum's swing. From the first scientific investigations of the pendulum around 1602 by Galileo Galilei, the regular motion of pendulums was used for timekeeping and was the world's most accurate timekeeping technology until the 1930s. The pendulum clock invented by Christiaan Huygens in 1658 became the world's standard timekeeper, used in homes and offices for 270 years, and ac ... [...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] |
