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Su-Shu Huang
Su-Shu Huang (, April 16, 1915 – September 15, 1977) was a Chinese-born American astrophysicist. A graduate of the University of Chicago, Huang began his career with the study of the continuous absorption coefficients of two-electron systems, but eventually his research focus turned to the study of stellar atmospheres, radiative transfer, and binary and multiple star systems. In subsequent years, Huang began to cover the topic of life on extrasolar planets and the prerequisites thereof, coining the term "habitable zone" to refer to the region around a star where planets could support liquid water at their surfaces at a 1959 conference of the Astronomical Society of the Pacific. Education and career A native of China, Huang earned his master's degree at Tsing Hua University, lecturing in astronomy at that institution from 1943 to 1947 before immigrating to the United States, earning a doctorate in astronomy from the University of Chicago in 1949. After teaching ast ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Changshu
Changshu (; Suzhounese: /d͡ʐan¹³ ʐoʔ²³/) is a county-level city under the jurisdiction of Suzhou, Jiangsu province, and is part of the Yangtze River Delta. It borders the prefecture-level city of Nantong to the northeast across the Yangtze River. Due to the mild climate and terrain there, it has enjoyed a high level of agricultural civilization since ancient times, and is named after this, for the first character of its name () means "always, often", while the second () means "ripe". The name of the adjacent county-level city of Taicang means "great granary". History Changshu first became an independent county in 540 AD, but in 581 was made subordinate to Suzhou. It was promoted to seat of a full prefecture in 1295, was rebuilt and fortified in the 14th century, but in 1370 was reduced again to the level of a county. In the 15th and 16th centuries Changshu was several times attacked by Japanese pirates. Changshu has traditionally been a market town for locally produced ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Extraterrestrial Life
Extraterrestrial life, colloquially referred to as alien life, is life that may occur outside Earth and which did not originate on Earth. No extraterrestrial life has yet been conclusively detected, although efforts are underway. Such life might range from simple forms like prokaryotes to intelligent beings, possibly bringing forth civilizations that might be far more advanced than humankind. The Drake equation speculates about the existence of sapient life elsewhere in the universe. The science of extraterrestrial life is known as astrobiology. Speculation about the possibility of inhabited "worlds" outside the planet Earth dates back to antiquity. Multiple early Christian writers discussed the idea of a "plurality of worlds" as proposed by earlier thinkers such as Democritus; Augustine references Epicurus's idea of innumerable worlds "throughout the boundless immensity of space" (originally expressed in his Letter to Herodotus) in ''The City of God''. In his first century p ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Planetary Habitability
Planetary habitability is the measure of a planet's or a natural satellite's potential to develop and maintain environments hospitable to life. Life may be generated directly on a planet or satellite endogenously or be transferred to it from another body, through a hypothetical process known as panspermia. Environments do not need to contain life to be considered habitable nor are accepted habitable zones (HZ) the only areas in which life might arise. As the existence of life beyond Earth is unknown, planetary habitability is largely an extrapolation of conditions on Earth and the characteristics of the Sun and Solar System which appear favorable to life's flourishing. Of particular interest are those factors that have sustained complex, multicellular organisms on Earth and not just simpler, unicellular creatures. Research and theory in this regard is a component of a number of natural sciences, such as astronomy, planetary science and the emerging discipline of astrobio ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Northwestern University Library
Northwestern University Libraries is the main academic library system of Northwestern University. The library holds 7.9 million item including 228,505 maps, 107,446 print journals and 173,089 electronic journals, making it the 11th largest library at a private university.June 6, 2007 "Google Project Will Create Digital Repository for Select University Library Collections/ref> The building was designed in Brutalist architecture, brutalist style by Walter Netsch of Skidmore, Owings & Merrill. Construction started in 1966 and the library opened in 1970. University Library succeeded Deering Library as the main library on campus and is connected to it. Along with the other institutions in the Big Ten Academic Alliance, Committee on Institutional Cooperation, University Library joined the Google Books, Google Book Search project on June 6, 2007. Library Collections *Melville J. Herskovits Library of African Studies: established in 1954, and named after Melville J. Herskovits, the Hersk ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Maryland
Maryland ( ) is a state in the Mid-Atlantic region of the United States. It shares borders with Virginia, West Virginia, and the District of Columbia to its south and west; Pennsylvania to its north; and Delaware and the Atlantic Ocean to its east. Baltimore is the largest city in the state, and the capital is Annapolis. Among its occasional nicknames are '' Old Line State'', the ''Free State'', and the '' Chesapeake Bay State''. It is named after Henrietta Maria, the French-born queen of England, Scotland, and Ireland, who was known then in England as Mary. Before its coastline was explored by Europeans in the 16th century, Maryland was inhabited by several groups of Native Americans – mostly by Algonquian peoples and, to a lesser degree, Iroquoian and Siouan. As one of the original Thirteen Colonies of England, Maryland was founded by George Calvert, 1st Baron Baltimore, a Catholic convert"George Calvert and Cecilius Calvert, Barons Baltimore" William Hand Browne, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Habitable Zone
In astronomy and astrobiology, the circumstellar habitable zone (CHZ), or simply the habitable zone, is the range of orbits around a star within which a planetary surface can support liquid water given sufficient atmospheric pressure.J. F. Kasting, D. P. Whitmire, R. T. Reynolds, Icarus 101, 108 (1993). The bounds of the CHZ are based on Earth's position in the Solar System and the amount of radiant energy it receives from the Sun. Due to the importance of liquid water to Earth's biosphere, the nature of the CHZ and the objects within it may be instrumental in determining the scope and distribution of planets capable of supporting Earth-like extraterrestrial life and intelligence. The habitable zone is also called the Goldilocks zone, a metaphor, allusion and antonomasia of the children's fairy tale of "Goldilocks and the Three Bears", in which a little girl chooses from sets of three items, ignoring the ones that are too extreme (large or small, hot or cold, etc.), and settl ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Extrasolar Planet
An exoplanet or extrasolar planet is a planet outside the Solar System. The first possible evidence of an exoplanet was noted in 1917 but was not recognized as such. The first confirmation of detection occurred in 1992. A different planet, initially detected in 1988, was confirmed in 2003. There are many methods of detecting exoplanets. Transit (astronomy), Transit photometry and Doppler spectroscopy have found the most, but these methods suffer from a clear observational bias favoring the detection of planets near the star; thus, 85% of the exoplanets detected are inside the tidal locking zone. In several cases, List of multiplanetary systems, multiple planets have been observed around a star. About 1 in 5 Solar analog, Sun-like starsFor the purpose of this 1 in 5 statistic, "Sun-like" means G-type star. Data for Sun-like stars was not available so this statistic is an extrapolation from data about K-type star, K-type stars. have an "Earth-sized"For the purpose of this 1 in 5 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Multiple Star System
A star system or stellar system is a small number of stars that orbit each other, bound by gravitational attraction. A large group of stars bound by gravitation is generally called a '' star cluster'' or '' galaxy'', although, broadly speaking, they are also star systems. Star systems are not to be confused with planetary systems, which include planets and similar bodies (such as comets). A star system of two stars is known as a '' binary star'', ''binary star system'' or ''physical double star''. If there are no tidal effects, no perturbation from other forces, and no transfer of mass from one star to the other, such a system is stable, and both stars will trace out an elliptical orbit around the barycenter of the system indefinitely. ''(See Two-body problem)''. Examples of binary systems are Sirius, Procyon and Cygnus X-1, the last of which probably consists of a star and a black hole. Multiple star systems A multiple star system consists of three or more stars that a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Binary Star
A binary star is a system of two stars that are gravitationally bound to and in orbit around each other. Binary stars in the night sky that are seen as a single object to the naked eye are often resolved using a telescope as separate stars, in which case they are called ''visual binaries''. Many visual binaries have long orbital periods of several centuries or millennia and therefore have orbits which are uncertain or poorly known. They may also be detected by indirect techniques, such as spectroscopy (''spectroscopic binaries'') or astrometry (''astrometric binaries''). If a binary star happens to orbit in a plane along our line of sight, its components will eclipse and transit each other; these pairs are called ''eclipsing binaries'', or, together with other binaries that change brightness as they orbit, ''photometric binaries''. If components in binary star systems are close enough they can gravitationally distort their mutual outer stellar atmospheres. In some cases, thes ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Radiative Zone
A radiation zone, or radiative region is a layer of a star's interior where energy is primarily transported toward the exterior by means of radiative diffusion and thermal conduction, rather than by convection. Energy travels through the radiation zone in the form of electromagnetic radiation as photons. Matter in a radiation zone is so dense that photons can travel only a short distance before they are absorbed or scattered by another particle, gradually shifting to longer wavelength as they do so. For this reason, it takes an average of 171,000 years for gamma rays from the core of the Sun to leave the radiation zone. Over this range, the temperature of the plasma drops from 15 million K near the core down to 1.5 million K at the base of the convection zone. Temperature gradient In a radiative zone, the temperature gradient—the change in temperature (''T'') as a function of radius (''r'')—is given by: : \frac\ =\ -\frac where ''κ''(''r'') is the opacity, ''ρ''(''r'') ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Stellar Atmosphere
The stellar atmosphere is the outer region of the volume of a star, lying above the stellar core, radiation zone and convection zone. Overview The stellar atmosphere is divided into several regions of distinct character: * The photosphere, which is the atmosphere's lowest and coolest layer, is normally its only visible part. Light escaping from the surface of the star stems from this region and passes through the higher layers. The Sun's photosphere has a temperature in the 5,770 K to 5,780 K range. Starspots, cool regions of disrupted magnetic field lie on the photosphere. * Above the photosphere lies the chromosphere. This part of the atmosphere first cools down and then starts to heat up to about 10 times the temperature of the photosphere. * Above the chromosphere lies the transition region, where the temperature increases rapidly on a distance of only around 100 km. * The outermost part of the stellar atmosphere is the corona, a tenuous plasma which has a tem ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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