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Heber Doust Curtis
Heber Doust Curtis (June 27, 1872 – January 9, 1942) was an American astronomer. He participated in 11 expeditions for the study of solar eclipses, and, as an advocate and theorist that additional galaxies existed outside of the Milky Way, was involved in the 1920 Shapley–Curtis Debate concerning the size and galactic structure of the universe. Biography Curtis was born on June 27, 1872, the elder son of Orson Blair Curtis and Sarah Eliza Doust. He studied at the University of Michigan and at the University of Virginia The University of Virginia (UVA) is a Public university#United States, public research university in Charlottesville, Virginia. Founded in 1819 by Thomas Jefferson, the university is ranked among the top academic institutions in the United S ..., earning a degree in astronomy from the latter. From 1902 to 1920 Curtis worked at Lick Observatory, continuing the survey of nebulae initiated by James Edward Keeler, Keeler. He headed up the Manuel Foste ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Muskegon, Michigan
Muskegon ( ') is a city in Michigan. It is the county seat of Muskegon County. Muskegon is known for fishing, sailing regattas, pleasure boating, and as a commercial and cruise ship port. It is a popular vacation destination because of the expansive freshwater beaches, historic architecture, and public art collection. It is the most populous city along the western shore of Michigan. At the 2020 United States Census the city population was 38,318. It is at the southwest corner of Muskegon Township, but is administratively autonomous. Muskegon is the center of the Muskegon Metropolitan Statistical Area, which is coextensive with Muskegon County and had a population of 173,566 in 2019. It is also part of the larger Grand Rapids- Kentwood-Muskegon-Combined Statistical Area with a population of 1,433,288. History Early inhabitants Human occupation of the Muskegon area goes back seven or eight thousand years to the nomadic Paleo-Indian hunters who occupied the area following ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Messier 87
Messier 87 (also known as Virgo A or NGC 4486, generally abbreviated to M87) is a supergiant elliptical galaxy with several trillion stars in the constellation Virgo. One of the largest and most massive galaxies in the local universe, it has a large population of globular clusters — about 15,000 compared with the 150–200 orbiting the Milky Way — and a jet of energetic plasma that originates at the core and extends at least , traveling at a relativistic speed. It is one of the brightest radio sources in the sky and a popular target for both amateur and professional astronomers. The French astronomer Charles Messier discovered M87 in 1781, and cataloged it as a nebula. M87 is about from Earth and is the second-brightest galaxy within the northern Virgo Cluster, having many satellite galaxies. Unlike a disk-shaped spiral galaxy, M87 has no distinctive dust lanes. Instead, it has an almost featureless, ellipsoidal shape typical of most giant elliptical gala ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Theory Of Relativity
The theory of relativity usually encompasses two interrelated theories by Albert Einstein: special relativity and general relativity, proposed and published in 1905 and 1915, respectively. Special relativity applies to all physical phenomena in the absence of gravity. General relativity explains the law of gravitation and its relation to the forces of nature. It applies to the cosmological and astrophysical realm, including astronomy. The theory transformed theoretical physics and astronomy during the 20th century, superseding a 200-year-old Classical mechanics, theory of mechanics created primarily by Isaac Newton. It introduced concepts including 4-dimensional spacetime as a unified entity of space and time in physics, time, relativity of simultaneity, kinematics, kinematic and gravity, gravitational time dilation, and length contraction. In the field of physics, relativity improved the science of elementary particles and their fundamental interactions, along with ushering in ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lake Angelus
Lake Angelus is a city in Oakland County in the U.S. state of Michigan. It is an affluent suburb of Detroit, with one of the highest per capita incomes of any community in the state. History In the early 1900s, a small community formed around the lake, then called Three Mile Lake. During the 1920s, the lake was renamed Lake Angelus by Mrs. Sollace B. Collidge as the original name stood for the distance from the eastern side of the lake shore to the western shore. The community was under pressure from nearby government establishments to be annexed. In 1929, however, a special state act of legislation was passed, granting Lake Angelus incorporation as a village. Lake Angelus became a city of its own in 1984. Geography According to the United States Census Bureau, the city has a total area of , of which is land and (34.36%) is water. The city completely surrounds the lake of the same name. The city is bordered: * To the north and east by the city of Auburn Hills * To the south b ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ann Arbor
Anne, alternatively spelled Ann, is a form of the Latin female given name Anna (name), Anna. This in turn is a representation of the Hebrew Hannah (given name), Hannah, which means 'favour' or 'grace'. Related names include Annie (given name), Annie. Anne is sometimes used as a male name in the Netherlands, particularly in the Friesland, Frisian speaking part (for example, author Anne de Vries). In this incarnation, it is related to Arne (name), Germanic arn-names and means 'eagle'.See entry on "Anne" in th''Behind the Name'' databaseand th"Anne"an"Ane"entries (in Dutch) in the Nederlandse Voornamenbank (Dutch First Names Database) of the Meertens Instituut (23 October 2018). It has also been used for males in France (Anne de Montmorency) and Scotland (Lord Anne Hamilton). Anne is a common name and the following lists represent a small selection. For a comprehensive list, see instead: . As a feminine name Anne * Saint Anne, Mother of the Virgin Mary * Anne, Queen of Great Bri ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Great Depression
The Great Depression (19291939) was an economic shock that impacted most countries across the world. It was a period of economic depression that became evident after a major fall in stock prices in the United States. The economic contagion began around September and led to the Wall Street stock market crash of October 24 (Black Thursday). It was the longest, deepest, and most widespread depression of the 20th century. Between 1929 and 1932, worldwide gross domestic product (GDP) fell by an estimated 15%. By comparison, worldwide GDP fell by less than 1% from 2008 to 2009 during the Great Recession. Some economies started to recover by the mid-1930s. However, in many countries, the negative effects of the Great Depression lasted until the beginning of World War II. Devastating effects were seen in both rich and poor countries with falling personal income, prices, tax revenues, and profits. International trade fell by more than 50%, unemployment in the U.S. rose to 23% and ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Centimetre
330px, Different lengths as in respect to the Electromagnetic spectrum, measured by the Metre and its deriveds scales. The Microwave are in-between 1 meter to 1 millimeter. A centimetre (international spelling) or centimeter (American spelling) (SI symbol cm) is a Units of measurement, unit of length in the International System of Units (SI), equal to one hundredth of a metre, ''centi'' being the SI prefix for a factor of . The centimetre was the base unit of length in the now deprecated centimetre–gram–second (CGS) system of units. Though for many physical quantities, SI prefixes for factors of 103—like ''milli-'' and ''kilo-''—are often preferred by technicians, the centimetre remains a practical unit of length for many everyday measurements. A centimetre is approximately the width of the fingernail of an average adult person. Equivalence to other units of length : One millilitre is defined as one cubic centimetre, under the SI system of units. Other uses In ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Inch
Measuring tape with inches The inch (symbol: in or ″) is a unit of length in the British imperial and the United States customary systems of measurement. It is equal to yard or of a foot. Derived from the Roman uncia ("twelfth"), the word ''inch'' is also sometimes used to translate similar units in other measurement systems, usually understood as deriving from the width of the human thumb. Standards for the exact length of an inch have varied in the past, but since the adoption of the international yard during the 1950s and 1960s the inch has been based on the metric system and defined as exactly 25.4 mm. Name The English word "inch" ( ang, ynce) was an early borrowing from Latin ' ("one-twelfth; Roman inch; Roman ounce"). The vowel change from Latin to Old English (which became Modern English ) is known as umlaut. The consonant change from the Latin (spelled ''c'') to English is palatalisation. Both were features of Old English phonology; see and fo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Milky Way
The Milky Way is the galaxy that includes our Solar System, with the name describing the galaxy's appearance from Earth: a hazy band of light seen in the night sky formed from stars that cannot be individually distinguished by the naked eye. The term ''Milky Way'' is a translation of the Latin ', from the Greek ('), meaning "milky circle". From Earth, the Milky Way appears as a band because its disk-shaped structure is viewed from within. Galileo Galilei first resolved the band of light into individual stars with his telescope in 1610. Until the early 1920s, most astronomers thought that the Milky Way contained all the stars in the Universe. Following the 1920 Great Debate between the astronomers Harlow Shapley and Heber Curtis, observations by Edwin Hubble showed that the Milky Way is just one of many galaxies. The Milky Way is a barred spiral galaxy with an estimated D25 isophotal diameter of , but only about 1,000 light years thick at the spiral arms (more at the bulg ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Galaxy
A galaxy is a system of stars, stellar remnants, interstellar gas, dust, dark matter, bound together by gravity. The word is derived from the Greek ' (), literally 'milky', a reference to the Milky Way galaxy that contains the Solar System. Galaxies, averaging an estimated 100 million stars, range in size from dwarfs with less than a hundred million stars, to the largest galaxies known – supergiants with one hundred trillion stars, each orbiting its galaxy's center of mass. Most of the mass in a typical galaxy is in the form of dark matter, with only a few percent of that mass visible in the form of stars and nebulae. Supermassive black holes are a common feature at the centres of galaxies. Galaxies are categorized according to their visual morphology as elliptical, spiral, or irregular. Many are thought to have supermassive black holes at their centers. The Milky Way's central black hole, known as Sagittarius A*, has a mass four million times greater than the Sun. As o ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Harlow Shapley
Harlow Shapley (November 2, 1885 – October 20, 1972) was an American scientist, head of the Harvard College Observatory (1921–1952), and political activist during the latter New Deal and Fair Deal. Shapley used Cepheid variable stars to estimate the size of the Milky Way Galaxy and the Sun's position within it by using parallax.Bart J. Bok. Harlow Shapely 1885–1972 A Biographical Memoir. National Academy of Sciences In 1953 he proposed his "liquid water belt" theory, now known as the concept of a habitable zone.Richard J. Hugget, ''uGeoecology: an evolutionary approach''. p. 10 Background Shapley was born on a farm five miles outside Nashville, Missouri, to Willis and Sarah (née Stowell) Shapley. He went to school in Jasper, Missouri, but not beyond elementary school. He worked as a journalist after studying at home and covering crime stories as a newspaper reporter for the ''Daily Sun'' in Chanute, Kansas, and intermittently for the ''Times'' of Joplin, Missouri. In Chanu ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Great Debate (astronomy)
The Great Debate, also called the Shapley–Curtis Debate, was held on 26 April 1920 at the Smithsonian Museum of Natural History, between the astronomers Harlow Shapley and Heber Curtis. It concerned the nature of so-called spiral nebulae and the size of the universe. Shapley believed that these nebulae were relatively small and lay within the outskirts of the Milky Way galaxy (then thought to be the entire universe), while Curtis held that they were in fact independent galaxies, implying that they were exceedingly large and distant. The two scientists first presented independent technical papers about "The Scale of the Universe" during the day and then took part in a joint discussion that evening. Much of the lore of the Great Debate grew out of two papers published by Shapley and by Curtis in the May 1921 issue of the ''Bulletin of the National Research Council''. The published papers each included counter arguments to the position advocated by the other scientist at the 1920 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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