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Harlan Smith
Harlan James Smith (August 25, 1924 – October 17, 1991) was an American astronomer. He served as director of the University of Texas McDonald Observatory from 1963 to 1989, where, among other accomplishments, he initiated the construction of the Harlan J. Smith Telescope, a 2.7-meter (107-inch) reflector now bearing his name . He came to McDonald Observatory as director in 1963, when he was also named chair of the University of Texas Astronomy Department in Austin, Texas. McDonald Observatory itself is located 440 miles west of Austin, in the Davis Mountains of West Texas. As head of the observatory, Smith's first major act was to obtain the funds needed to build the 2.7m telescope. Toward that end, he persuaded NASA the telescope was needed in support of space missions to the planets. The telescope brought new life to the observatory and helped recruit young faculty members, establishing McDonald as key player in the exploration of the solar system. In 1991, Smith received the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
World War II
World War II or the Second World War, often abbreviated as WWII or WW2, was a world war that lasted from 1939 to 1945. It involved the vast majority of the world's countries—including all of the great powers—forming two opposing military alliances: the Allies and the Axis powers. World War II was a total war that directly involved more than 100 million personnel from more than 30 countries. The major participants in the war threw their entire economic, industrial, and scientific capabilities behind the war effort, blurring the distinction between civilian and military resources. Aircraft played a major role in the conflict, enabling the strategic bombing of population centres and deploying the only two nuclear weapons ever used in war. World War II was by far the deadliest conflict in human history; it resulted in 70 to 85 million fatalities, mostly among civilians. Tens of millions died due to genocides (including the Holocaust), starvation, ma ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Harlan (crater)
Harlan is a lunar impact crater near the southeastern limb of the Moon. It is located just to the northeast of the crater Marinus. To the northeast is the flooded walled plain Abel, and to the southeast is Mare Australe. This crater has a worn outer rim, with a crater attached to the northeastern rim and an irregular southern edge. The inner wall has slumped to form a shelf along the northwestern side. The interior floor has been resurfaced by basaltic lava, producing a level, nearly featureless surface with a lower albedo than its surroundings. Harlan was previously designated Marinus D before being assigned its current name by the IAU The International Astronomical Union (IAU; french: link=yes, Union astronomique internationale, UAI) is a nongovernmental organisation with the objective of advancing astronomy in all aspects, including promoting astronomical research, outreach .... References * * * * * * * * * * * * {{refend Impact craters on the Moon ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
3842 Harlansmith
__NOTOC__ Year 384 ( CCCLXXXIV) was a leap year starting on Monday (link will display the full calendar) of the Julian calendar. At the time, it was known as the Year of the Consulship of Ricomer and Clearchus (or, less frequently, year 1137 '' Ab urbe condita''). The denomination 384 for this year has been used since the early medieval period, when the Anno Domini calendar era became the prevalent method in Europe for giving names to years. Events By place Roman Empire * Magnus Maximus elevates his son Flavius Victor to the rank of ''Augustus''. * Magnus Maximus returns to Britain, to aid the Roman army with the barbarian raids triggered by Maximus' withdrawal of troops to the continent. * The Forum of Theodosius ("Forum of the Bull") is built in Constantinople. * Quintus Aurelius Symmachus becomes urban prefect of Rome. * An edict of Theodosius I closes pagan temples in the Nile Valley (Egypt). * Stilicho marries Serena, adopted niece of Theodosius I. Persia ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Asteroid
An asteroid is a minor planet of the inner Solar System. Sizes and shapes of asteroids vary significantly, ranging from 1-meter rocks to a dwarf planet almost 1000 km in diameter; they are rocky, metallic or icy bodies with no atmosphere. Of the roughly one million known asteroids the greatest number are located between the orbits of Mars and Jupiter, approximately 2 to 4 AU from the Sun, in the main asteroid belt. Asteroids are generally classified to be of three types: C-type, M-type, and S-type. These were named after and are generally identified with carbonaceous, metallic, and silicaceous compositions, respectively. The size of asteroids varies greatly; the largest, Ceres, is almost across and qualifies as a dwarf planet. The total mass of all the asteroids combined is only 3% that of Earth's Moon. The majority of main belt asteroids follow slightly elliptical, stable orbits, revolving in the same direction as the Earth and taking from three to six years to comple ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cancer
Cancer is a group of diseases involving abnormal cell growth with the potential to invade or spread to other parts of the body. These contrast with benign tumors, which do not spread. Possible signs and symptoms include a lump, abnormal bleeding, prolonged cough, unexplained weight loss, and a change in bowel movements. While these symptoms may indicate cancer, they can also have other causes. Over 100 types of cancers affect humans. Tobacco use is the cause of about 22% of cancer deaths. Another 10% are due to obesity, poor diet, lack of physical activity or excessive drinking of alcohol. Other factors include certain infections, exposure to ionizing radiation, and environmental pollutants. In the developing world, 15% of cancers are due to infections such as ''Helicobacter pylori'', hepatitis B, hepatitis C, human papillomavirus infection, Epstein–Barr virus and human immunodeficiency virus (HIV). These factors act, at least partly, by changing the genes of ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Delta Scuti Variable
A Delta Scuti variable (sometimes termed dwarf cepheid when the V-band amplitude is larger than 0.3 mag.) is a subclass of young pulsating star. These variables as well as classical cepheids are important standard candles and have been used to establish the distance to the Large Magellanic Cloud, globular clusters, open clusters, and the Galactic Center. The variables follow a period-luminosity relation in certain passbands like other standard candles such as Cepheids. SX Phoenicis variables are generally considered to be a subclass of Delta Scuti variables that contain old stars, and can be found in globular clusters. SX Phe variables also follow a period-luminosity relation. One last sub-class are the pre-main sequence (PMS) Delta Scuti variables. The OGLE and MACHO surveys have detected nearly 3000 Delta Scuti variables in the Large Magellanic Cloud. Typical brightness fluctuations are from 0.003 to 0.9 magnitudes in V over a period of a few hours, although the amplitude ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Quasar
A quasar is an extremely Luminosity, luminous active galactic nucleus (AGN). It is pronounced , and sometimes known as a quasi-stellar object, abbreviated QSO. This emission from a galaxy nucleus is powered by a supermassive black hole with a mass ranging from millions to tens of billions of solar masses, surrounded by a gaseous accretion disc. Gas in the disc falling towards the black hole heats up because of friction and releases energy in the form of electromagnetic radiation. The radiant energy of quasars is enormous; the most powerful quasars have luminosity, luminosities thousands of times greater than that of a galaxy such as the Milky Way. Usually, quasars are categorized as a subclass of the more general category of AGN. The redshifts of quasars are of Expansion of the universe, cosmological origin. The term originated as a Contraction (grammar), contraction of "quasi-stellar ''[star-like]'' radio source"—because quasars were first identified during the 1950s as sour ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dorrit Hoffleit
Ellen Dorrit Hoffleit (March 12, 1907 – April 9, 2007) was an American senior research astronomer at Yale University. She is best known for her work in variable stars, astrometry, spectroscopy, meteors, and the Bright Star Catalog. She is also known for her mentorship of many young women and generations of astronomers. Life Hoffleit's interest in astronomy began with the 1919 Perseid meteor shower that she saw with her mother. In 1928, she graduated cum laude with a B.A. in mathematics. She then went on to work for the Harvard College Observatory, searching for variable stars. In 1938, she was awarded a Ph.D. in astronomy from Radcliffe College and was subsequently hired, in 1948, as an astronomer at Harvard University. She remained at Harvard until 1956 when she moved to Yale University. She remained at Yale until retirement in 1975. At Yale she followed in the footsteps of Ida Barney, taking over her astrometric work, and of whom she later wrote "To know erwas a pleasu ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Photometry (astronomy)
Photometry, from Greek '' photo-'' ("light") and '' -metry'' ("measure"), is a technique used in astronomy that is concerned with measuring the flux or intensity of light radiated by astronomical objects. This light is measured through a telescope using a photometer, often made using electronic devices such as a CCD photometer or a photoelectric photometer that converts light into an electric current by the photoelectric effect. When calibrated against standard stars (or other light sources) of known intensity and colour, photometers can measure the brightness or apparent magnitude of celestial objects. The methods used to perform photometry depend on the wavelength region under study. At its most basic, photometry is conducted by gathering light and passing it through specialized photometric optical bandpass filters, and then capturing and recording the light energy with a photosensitive instrument. Standard sets of passbands (called a photometric system) are defined to allow a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Variable Star
A variable star is a star whose brightness as seen from Earth (its apparent magnitude) changes with time. This variation may be caused by a change in emitted light or by something partly blocking the light, so variable stars are classified as either: * Intrinsic variables, whose luminosity actually changes; for example, because the star periodically swells and shrinks. * Extrinsic variables, whose apparent changes in brightness are due to changes in the amount of their light that can reach Earth; for example, because the star has an orbiting companion that sometimes eclipses it. Many, possibly most, stars have at least some variation in luminosity: the energy output of the Sun, for example, varies by about 0.1% over an 11-year solar cycle. Discovery An ancient Egyptian calendar of lucky and unlucky days composed some 3,200 years ago may be the oldest preserved historical document of the discovery of a variable star, the eclipsing binary Algol. Of the modern astronomers, th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Yale University
Yale University is a private research university in New Haven, Connecticut. Established in 1701 as the Collegiate School, it is the third-oldest institution of higher education in the United States and among the most prestigious in the world. It is a member of the Ivy League. Chartered by the Connecticut Colony, the Collegiate School was established in 1701 by clergy to educate Congregational ministers before moving to New Haven in 1716. Originally restricted to theology and sacred languages, the curriculum began to incorporate humanities and sciences by the time of the American Revolution. In the 19th century, the college expanded into graduate and professional instruction, awarding the first PhD in the United States in 1861 and organizing as a university in 1887. Yale's faculty and student populations grew after 1890 with rapid expansion of the physical campus and scientific research. Yale is organized into fourteen constituent schools: the original undergraduate col ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
