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SN Refsdal
SN Refsdal is the first detected multiply-lensed supernova, visible within the field of the galaxy cluster MACS J1149+2223. It was named after Norwegian astrophysicist Sjur Refsdal, who, in 1964, first proposed using time-delayed images from a lensed supernova to study the expansion of the universe. The observations were made using the Hubble Space Telescope. Einstein cross The host galaxy of SN Refsdal is at a redshift of 1.49, corresponding to a comoving distance of 14.4 billion light-years and a lookback time of 9.34 billion years. The multiple images are arranged around the elliptical galaxy at z = 0.54 in a cross-shaped pattern, also known as an " Einstein cross". Reappearance After the discovery of the supernova, astronomers predicted that they would be able to see it again in about one year, after the four images had faded away. This is because the initially observed four-image pattern was only one component of the lensing display. The supernova may also have appeared ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] [Amazon] |
The Past, Present And Future Appearances Of The Refsdal Supernova
''The'' is a grammatical article in English, denoting nouns that are already or about to be mentioned, under discussion, implied or otherwise presumed familiar to listeners, readers, or speakers. It is the definite article in English. ''The'' is the most frequently used word in the English language; studies and analyses of texts have found it to account for seven percent of all printed English-language words. It is derived from gendered articles in Old English which combined in Middle English and now has a single form used with nouns of any gender. The word can be used with both singular and plural nouns, and with a noun that starts with any letter. This is different from many other languages, which have different forms of the definite article for different genders or numbers. Pronunciation In most dialects, "the" is pronounced as (with the voiced dental fricative followed by a schwa) when followed by a consonant sound, and as (homophone of the archaic pronoun ''thee'') ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] [Amazon] |
Los Angeles Times
The ''Los Angeles Times'' is an American Newspaper#Daily, daily newspaper that began publishing in Los Angeles, California, in 1881. Based in the Greater Los Angeles city of El Segundo, California, El Segundo since 2018, it is the List of newspapers in the United States, sixth-largest newspaper in the U.S. and the largest in the Western United States with a print circulation of 118,760. It has 500,000 online subscribers, the fifth-largest among U.S. newspapers. Owned by Patrick Soon-Shiong and published by California Times, the paper has won over 40 Pulitzer Prizes since its founding. In the 19th century, the paper developed a reputation for civic boosterism and opposition to Trade union, labor unions, the latter of which led to the Los Angeles Times bombing, bombing of its headquarters in 1910. The paper's profile grew substantially in the 1960s under publisher Otis Chandler, who adopted a more national focus. As with other regional newspapers in California and the United Sta ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] [Amazon] |
Supernovae
A supernova (: supernovae or supernovas) is a powerful and luminous explosion of a star. A supernova occurs during the last evolutionary stages of a massive star, or when a white dwarf is triggered into runaway nuclear fusion. The original object, called the ''progenitor'', either collapses to a neutron star or black hole, or is completely destroyed to form a diffuse nebula. The peak optical luminosity of a supernova can be comparable to that of an entire galaxy before fading over several weeks or months. The last supernova directly observed in the Milky Way was Kepler's Supernova in 1604, appearing not long after Tycho's Supernova in 1572, both of which were visible to the naked eye. The remnants of more recent supernovae have been found, and observations of supernovae in other galaxies suggest they occur in the Milky Way on average about three times every century. A supernova in the Milky Way would almost certainly be observable through modern astronomical telescopes. Th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] [Amazon] |
National Geographic Society
The National Geographic Society, headquartered in Washington, D.C., United States, is one of the largest nonprofit scientific and educational organizations in the world. Founded in 1888, its interests include geography, archaeology, natural science, the promotion of environmental protection, environmental and historical preservation, historical conservation movement, conservation, and the study of civilization, world culture and World history (field), history. The National Geographic Society's logo is a yellow page orientation, portrait frame—rectangular in shape—which appears on the Margin (typography), margins surrounding the front covers of its magazines and as its television channel logo. Through National Geographic Partners (a joint venture with The Walt Disney Company), the Society operates the National Geographic, magazine, National Geographic Global Networks, TV channels, a website, worldwide events, and other media operations. Overview The National Geographic S ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] [Amazon] |
Hubble Constant
Hubble's law, also known as the Hubble–Lemaître law, is the observation in physical cosmology that galaxies are moving away from Earth at speeds proportional to their distance. In other words, the farther a galaxy is from the Earth, the faster it moves away. A galaxy's recessional velocity is typically determined by measuring its redshift, a shift in the frequency of light emitted by the galaxy. The discovery of Hubble's law is attributed to work published by Edwin Hubble in 1929, but the notion of the universe expanding at a calculable rate was first derived from general relativity equations in 1922 by Alexander Friedmann. The Friedmann equations showed the universe might be expanding, and presented the expansion speed if that were the case. Before Hubble, astronomer Carl Wilhelm Wirtz had, in 1922 and 1924, deduced with his own data that galaxies that appeared smaller and dimmer had larger redshifts and thus that more distant galaxies recede faster from the observer. In ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] [Amazon] |
Wolfram Alpha
WolframAlpha ( ) is an answer engine developed by Wolfram Research. It is offered as an online service that answers factual queries by computing answers from externally sourced data. History Launch preparations for WolframAlpha began on May 15, 2009, at 7:00 pm CDT with a live broadcast on Justin.tv. The plan was to publicly launch the service a few hours later. However, there were issues due to extreme load. The service officially launched on May 18, 2009, receiving mixed reviews. The engine is based on Wolfram's earlier product Wolfram Mathematica, a technical computing platform. The coding is written in Wolfram Language, a general multi-paradigm programming language, and implemented in Mathematica. WolframAlpha gathers data from academic and commercial websites such as the CIA's ''The World Factbook'', the United States Geological Survey, a Cornell University Library publication called ''All About Birds'', '' Chambers Biographical Dictionary'', Dow Jones, the ''Cat ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] [Amazon] |
Cosmic Time
Cosmic time, or cosmological time, is the time coordinate used in the Big Bang models of physical cosmology. This concept of time avoids some issues related to relativity by being defined within a solution to the equations of general relativity widely used in cosmology. Problems with absolute time Albert Einstein's theory of special relativity showed that simultaneity is not absolute. An observer at rest may believe that two events separated in space (say, two lightning strikes 10 meters apart) occurred at the same time, while another observer in (relative) motion claims that one occurred after the other. This coupling of space and time, Minkowski spacetime, complicates scientific time comparisons: neither observer is an obvious candidate for the time reference. Einstein's theory of general relativity in an isotropic, homogeneous expanding universe provides a way to define a unique time reference. All coordinate points in such a universe are equivalent. Hermann Weyl postulated t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] [Amazon] |
Comoving Distance
In standard cosmology, comoving distance and proper distance (or physical distance) are two closely related distance measures used by cosmologists to define distances between objects. ''Comoving distance'' factors out the expansion of the universe, giving a distance that does not change in time except due to local factors, such as the motion of a galaxy within a cluster. ''Proper distance'' roughly corresponds to where a distant object would be at a specific moment of cosmological time, which can change over time due to the expansion of the universe. Comoving distance and proper distance are defined to be equal at the present time. At other times, the Universe's expansion results in the proper distance changing, while the comoving distance remains constant. Comoving coordinates Although general relativity allows the formulation of the laws of physics using arbitrary coordinates, some coordinate choices are easier to work with. Comoving coordinates are an example of such a coor ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] [Amazon] |
Hubble's Law
Hubble's law, also known as the Hubble–Lemaître law, is the observation in physical cosmology that galaxies are moving away from Earth at speeds proportional to their distance. In other words, the farther a galaxy is from the Earth, the faster it moves away. A galaxy's recessional velocity is typically determined by measuring its redshift, a shift in the frequency of light emitted by the galaxy. The discovery of Hubble's law is attributed to work published by Edwin Hubble in 1929, but the notion of the universe expanding at a calculable rate was first derived from general relativity equations in 1922 by Alexander Friedmann. The Friedmann equations showed the universe might be expanding, and presented the expansion speed if that were the case. Before Hubble, astronomer Carl Wilhelm Wirtz had, in 1922 and 1924, deduced with his own data that galaxies that appeared smaller and dimmer had larger redshifts and thus that more distant galaxies recede faster from the observer. In ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] [Amazon] |
New York Times
''The New York Times'' (''NYT'') is an American daily newspaper based in New York City. ''The New York Times'' covers domestic, national, and international news, and publishes opinion pieces, investigative reports, and reviews. As one of the longest-running newspapers in the United States, the ''Times'' serves as one of the country's Newspaper of record, newspapers of record. , ''The New York Times'' had 9.13 million total and 8.83 million online subscribers, both by significant margins the List of newspapers in the United States, highest numbers for any newspaper in the United States; the total also included 296,330 print subscribers, making the ''Times'' the second-largest newspaper by print circulation in the United States, following ''The Wall Street Journal'', also based in New York City. ''The New York Times'' is published by the New York Times Company; since 1896, the company has been chaired by the Ochs-Sulzberger family, whose current chairman and the paper's publ ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] [Amazon] |
