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John Huchra
John Peter Huchra ( ; December 23, 1948 – October 8, 2010) was an American astronomer and professor. He was the Vice Provost for Research Policy at Harvard University and a Professor of Astronomy at the Center for Astrophysics Harvard & Smithsonian.AAS Officers [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Boston
Boston (), officially the City of Boston, is the state capital and most populous city of the Commonwealth of Massachusetts, as well as the cultural and financial center of the New England region of the United States. It is the 24th- most populous city in the country. The city boundaries encompass an area of about and a population of 675,647 as of 2020. It is the seat of Suffolk County (although the county government was disbanded on July 1, 1999). The city is the economic and cultural anchor of a substantially larger metropolitan area known as Greater Boston, a metropolitan statistical area (MSA) home to a census-estimated 4.8 million people in 2016 and ranking as the tenth-largest MSA in the country. A broader combined statistical area (CSA), generally corresponding to the commuting area and including Providence, Rhode Island, is home to approximately 8.2 million people, making it the sixth most populous in the United States. Boston is one of the oldest ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Marc Aaronson
Marc Aaronson (24 August 1950 – 30 April 1987) was an American astronomer. Life Aaronson was born in Los Angeles. He was educated at the California Institute of Technology, where he received a BS in 1972. He completed his Ph.D. in 1977 at Harvard University with a dissertation on the near-infrared aperture photometry of galaxies. He joined Steward Observatory at the University of Arizona as a postdoctoral research associate in 1977 and became an Associate Professor of Astronomy in 1983. Aaronson and Jeremy Mould won the George Van Biesbroeck Prize in 1981 and the Newton Lacy Pierce Prize in Astronomy in 1984 from the American Astronomical Society. He was also awarded the Bart J. Bok Prize in 1983 from Harvard University. His work concentrated on three fields: the determination of the Hubble constant (H0) using the Tully–Fisher relation, the study of carbon rich stars, and the velocity distribution of those stars in dwarf spheroidal galaxies. Aaronson was one of ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Quasar
A quasar is an extremely 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 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 cosmological origin. The term originated as a contraction of "quasi-stellar '' tar-like' radio source"—because quasars were first identified during the 1950s as sources of radio-wave emission of unknown physical origin—and when identi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gravitational Lens
A gravitational lens is a distribution of matter (such as a cluster of galaxies) between a distant light source and an observer that is capable of bending the light from the source as the light travels toward the observer. This effect is known as gravitational lensing, and the amount of bending is one of the predictions of Albert Einstein's general theory of relativity. Treating light as corpuscles travelling at the speed of light, Newtonian physics also predicts the bending of light, but only half of that predicted by general relativity. Although Einstein made unpublished calculations on the subject in 1912, Orest Khvolson (1924) and Frantisek Link (1936) are generally credited with being the first to discuss the effect in print. However, this effect is more commonly associated with Einstein, who published an article on the subject in 1936. Fritz Zwicky posited in 1937 that the effect could allow galaxy clusters to act as gravitational lenses. It was not until 1979 that th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Science (journal)
''Science'', also widely referred to as ''Science Magazine'', is the peer-reviewed academic journal of the American Association for the Advancement of Science (AAAS) and one of the world's top academic journals. It was first published in 1880, is currently circulated weekly and has a subscriber base of around 130,000. Because institutional subscriptions and online access serve a larger audience, its estimated readership is over 400,000 people. ''Science'' is based in Washington, D.C., United States, with a second office in Cambridge, UK. Contents The major focus of the journal is publishing important original scientific research and research reviews, but ''Science'' also publishes science-related news, opinions on science policy and other matters of interest to scientists and others who are concerned with the wide implications of science and technology. Unlike most scientific journals, which focus on a specific field, ''Science'' and its rival ''Nature'' cover the full r ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
The San Diego Union
''The San Diego Union-Tribune'' is a metropolitan daily newspaper published in San Diego, California, that has run since 1868. Its name derives from a 1992 merger between the two major daily newspapers at the time, ''The San Diego Union'' and the ''San Diego Evening Tribune''. The name changed to ''U-T San Diego'' in 2012 but was changed again to ''The San Diego Union-Tribune'' in 2015. In 2015, it was acquired by Tribune Publishing. In February 2018 it was announced to be sold, along with the ''Los Angeles Times'', to Patrick Soon-Shiong's investment firm Nant Capital LLC for $500 million plus $90 million in pension liabilities. The sale was completed on June 18, 2018. History Predecessors The predecessor newspapers of the ''Union-Tribune'' were: * ''San Diego Herald'', founded 1851 and closed April 7, 1860; John Judson Ames was its first editor and proprietor. * ''San Diego Sun'', founded 1861 and merged with the ''Evening Tribune'' in 1939. * ''San Diego Union'', found ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Great Wall (astronomy)
The Great Wall (also called Coma Wall), sometimes specifically referred to as the CfA2 Great Wall, is an immense galaxy filament. It is one of the largest known superstructures in the observable universe. This structure was discovered c. 1989 by a team of American astronomers led by Margaret J. Geller and John Huchra while analyzing data gathered by the second CfA Redshift Survey of the Center for Astrophysics Harvard & Smithsonian (CfA). Characteristics The term "Great" has been added to distinguish it as an even larger type compared to standard galaxy walls. Great walls are so rare that only five or possibly six (if the disputed Hercules–Corona Borealis Great Wall is counted) of them have been discovered to date. The CfA2 Great Wall has the maximum dimensions of either 500 million or 750 million light years depending on the figure and the reference used. It is 200 million light years in width and about 16 million light years in thickness. Its nearest point is about 30 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Redshift Survey
In astronomy, a redshift survey is a survey of a section of the sky to measure the redshift of astronomical objects: usually galaxies, but sometimes other objects such as galaxy clusters or quasars. Using Hubble's law, the redshift can be used to estimate the distance of an object from Earth. By combining redshift with angular position data, a redshift survey maps the 3D distribution of matter within a field of the sky. These observations are used to measure detailed statistical properties of the large-scale structure of the universe. In conjunction with observations of early structure in the cosmic microwave background, these results can place strong constraints on cosmological parameters such as the average matter density and the Hubble constant. Generally the construction of a redshift survey involves two phases: first the selected area of the sky is imaged with a wide-field telescope, then galaxies brighter than a defined limit are selected from the resulting images as ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
CfA Redshift Survey
The Center for Astrophysics (CfA) Redshift Survey was the first attempt to map the large-scale structure of the universe. The first survey began in 1977 with the objective of calculating the velocities of the brighter galaxies in the nearby universe by measuring their redshifts at the Smithsonian Astrophysical Observatory in Cambridge, Massachusetts. The redshift is the relative increase in the wavelength emitted by a light source, in this case a galaxy, moving away from an observer from which its speed and then, using Hubble's Law, its distance can be calculated. A 3-dimensional map of that part of the Universe could thus be produced. This initial data collection was completed by 1982. The second survey (CfA2) was started in 1985 by John Huchra and Margaret Geller and measured the redshifts of 18,000 bright galaxies in the Northern sky by 1995. Data from the second CfA survey showed that galaxies were not evenly distributed but clustered on the spherical surfaces of empty "vo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Megaparsec
The parsec (symbol: pc) is a unit of length used to measure the large distances to astronomical objects outside the Solar System, approximately equal to or (au), i.e. . The parsec unit is obtained by the use of parallax and trigonometry, and is defined as the distance at which 1 au subtends an angle of one arcsecond ( of a degree). This corresponds to astronomical units, i.e. 1\, \mathrm = 1/\tan \left( \ \mathrm \right)\, \mathrm. The nearest star, Proxima Centauri, is about from the Sun. Most stars visible to the naked eye are within a few hundred parsecs of the Sun, with the most distant at a few thousand. The word ''parsec'' is a portmanteau of "parallax of one second" and was coined by the British astronomer Herbert Hall Turner in 1913 to make calculations of astronomical distances from only raw observational data easy for astronomers. Partly for this reason, it is the unit preferred in astronomy and astrophysics, though the light-year remains prominent in popular ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Margaret Geller
Margaret J. Geller (born December 8, 1947) is an American astrophysicist at the Center for Astrophysics Harvard & Smithsonian. Her work has included pioneering maps of the nearby universe, studies of the relationship between galaxies and their environment, and the development and application of methods for measuring the distribution of matter in the universe. Career Geller made pioneering maps of large-scale structure in the universe. Geller received a Bachelor of Arts degree in Physics at the University of California, Berkeley (1970) and a Ph.D. in Physics from Princeton (1974). Geller completed her doctoral dissertation, titled "Bright galaxies in rich clusters: a statistical model for magnitude distributions", under the supervision of James Peebles. Although Geller was thinking about studying solid state physics in graduate school, Charles Kittel suggested she go to Princeton to study astrophysics. After research fellowships at the Center for Astrophysics Harvard & Smith ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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