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Comet Morehouse
Comet Morehouse (modern formal designation: C/1908 R1) was a bright, non-periodic comet discovered by US astronomer Daniel Walter Morehouse and first observed on September 1, 1908. It was unusual in the rapid variations seen in the structure of its tail. At times, the tail seemed to split into up to six separate tails; at others, the tail appeared completely detached from the head of the comet. The tail was further unusual in that it formed while the comet was still 2 AU away from the Sun (where distances of 1.5 AU are more usual), and that there was a high concentration of the CO+ ion in its spectrum. As is typical for comets fresh from the Oort Cloud The Oort cloud (), sometimes called the Öpik–Oort cloud, first described in 1950 by the Dutch astronomer Jan Oort, is a theoretical concept of a cloud of predominantly icy planetesimals proposed to surround the Sun at distances ranging from 2 ..., its orbital solution is more or less parabolic; if its orbit is in fact close ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Postcard
A postcard or post card is a piece of thick paper or thin cardboard, typically rectangular, intended for writing and mailing without an envelope. Non-rectangular shapes may also be used but are rare. There are novelty exceptions, such as wooden postcards, copper postcards sold in the Copper Country of the U.S. state of Michigan, and coconut "postcards" from tropical islands. In some places, one can send a postcard for a lower fee than a letter. Stamp collectors distinguish between postcards (which require a postage stamp) and postal cards (which have the postage pre-printed on them). While a postcard is usually printed and sold by a private company, individual or organization, a postal card is issued by the relevant postal authority (often with pre-printed postage). Production of postcards blossomed in the late 19th and early 20th centuries. As an easy and quick way for individuals to communicate, they became extremely popular. The study and collecting of postcards is terme ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Daniel Walter Morehouse
Daniel is a masculine given name and a surname of Hebrew origin. It means "God is my judge"Hanks, Hardcastle and Hodges, ''Oxford Dictionary of First Names'', Oxford University Press, 2nd edition, , p. 68. (cf. Gabriel—"God is my strength"), and derives from two early biblical figures, primary among them Daniel from the Book of Daniel. It is a common given name for males, and is also used as a surname. It is also the basis for various derived given names and surnames. Background The name evolved into over 100 different spellings in countries around the world. Nicknames (Dan, Danny) are common in both English and Hebrew; "Dan" may also be a complete given name rather than a nickname. The name "Daniil" (Даниил) is common in Russia. Feminine versions (Danielle, Danièle, Daniela, Daniella, Dani, Danitza) are prevalent as well. It has been particularly well-used in Ireland. The Dutch names "Daan" and "Daniël" are also variations of Daniel. A related surname developed ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Astronomical Unit
The astronomical unit (symbol: au, or or AU) is a unit of length, roughly the distance from Earth to the Sun and approximately equal to or 8.3 light-minutes. The actual distance from Earth to the Sun varies by about 3% as Earth orbits the Sun, from a maximum (aphelion) to a minimum (perihelion) and back again once each year. The astronomical unit was originally conceived as the average of Earth's aphelion and perihelion; however, since 2012 it has been defined as exactly (see below for several conversions). The astronomical unit is used primarily for measuring distances within the Solar System or around other stars. It is also a fundamental component in the definition of another unit of astronomical length, the parsec. History of symbol usage A variety of unit symbols and abbreviations have been in use for the astronomical unit. In a 1976 resolution, the International Astronomical Union (IAU) had used the symbol ''A'' to denote a length equal to the astronomical ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Julian Year (astronomy)
In astronomy, a Julian year (symbol: a or aj) is a unit of measurement of time defined as exactly 365.25 days of SI seconds each.P. Kenneth Seidelmann, ed.''The explanatory supplement to the Astronomical Almanac'' (Mill Valley, Cal.: University Science Books, 1992), pp. 8, 696, 698–9, 704, 716, 730. Reprinted from the "IAU Style Manual" by G.A. Wilkinson, Comm. 5, in IAU Transactions XXB (1987).Harold Rabinowitz and Suzanne Vogel''The manual of scientific style''(Burlington, MA: Academic Press, 2009) 369. The length of the Julian year is the average length of the year in the Julian calendar that was used in Western societies until the adoption of the Gregorian Calendar, and from which the unit is named. Nevertheless, because astronomical Julian years are measuring duration rather than designating dates, this Julian year does not correspond to years in the Julian calendar or any other calendar. Nor does it correspond to the many other ways of defining a year. Usage The J ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Comet
A comet is an icy, small Solar System body that, when passing close to the Sun, warms and begins to release gases, a process that is called outgassing. This produces a visible atmosphere or coma, and sometimes also a tail. These phenomena are due to the effects of solar radiation and the solar wind acting upon the nucleus of the comet. Comet nuclei range from a few hundred meters to tens of kilometers across and are composed of loose collections of ice, dust, and small rocky particles. The coma may be up to 15 times Earth's diameter, while the tail may stretch beyond one astronomical unit. If sufficiently bright, a comet may be seen from Earth without the aid of a telescope and may subtend an arc of 30° (60 Moons) across the sky. Comets have been observed and recorded since ancient times by many cultures and religions. Comets usually have highly eccentric elliptical orbits, and they have a wide range of orbital periods, ranging from several years to potentially several mill ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Oort Cloud
The Oort cloud (), sometimes called the Öpik–Oort cloud, first described in 1950 by the Dutch astronomer Jan Oort, is a theoretical concept of a cloud of predominantly icy planetesimals proposed to surround the Sun at distances ranging from 2,000 to 200,000 AU (0.03 to 3.2 light-years).The Oort cloud's outer limit is difficult to define as it varies over the millennia as different stars pass the Sun and thus is subject to variation. Estimates of its distance range from 50,000 to 200,000 au. It is divided into two regions: a disc-shaped inner Oort cloud (or Hills cloud) and a spherical outer Oort cloud. Both regions lie beyond the heliosphere and are in interstellar space. The Kuiper belt, the scattered disc and the detached objects, the other three reservoirs of trans-Neptunian objects, are less than one thousandth as far from the Sun as the Oort cloud. The outer limit of the Oort cloud defines the cosmographic boundary of the Solar System and the extent of the Sun's Hill ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Parabola
In mathematics, a parabola is a plane curve which is mirror-symmetrical and is approximately U-shaped. It fits several superficially different mathematical descriptions, which can all be proved to define exactly the same curves. One description of a parabola involves a point (the focus) and a line (the directrix). The focus does not lie on the directrix. The parabola is the locus of points in that plane that are equidistant from both the directrix and the focus. Another description of a parabola is as a conic section, created from the intersection of a right circular conical surface and a plane parallel to another plane that is tangential to the conical surface. The line perpendicular to the directrix and passing through the focus (that is, the line that splits the parabola through the middle) is called the "axis of symmetry". The point where the parabola intersects its axis of symmetry is called the "vertex" and is the point where the parabola is most sharply curved. The ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Non-periodic Comets
A periodic function is a function that repeats its values at regular intervals. For example, the trigonometric functions, which repeat at intervals of 2\pi radians, are periodic functions. Periodic functions are used throughout science to describe oscillations, waves, and other phenomena that exhibit periodicity. Any function that is not periodic is called aperiodic. Definition A function is said to be periodic if, for some nonzero constant , it is the case that :f(x+P) = f(x) for all values of in the domain. A nonzero constant for which this is the case is called a period of the function. If there exists a least positive constant with this property, it is called the fundamental period (also primitive period, basic period, or prime period.) Often, "the" period of a function is used to mean its fundamental period. A function with period will repeat on intervals of length , and these intervals are sometimes also referred to as periods of the function. Geometrically, a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
1908 In Science
The year 1908 in science and technology involved some significant events, listed below. Archaeology * A 40,000-year-old Neanderthal boy skeleton is found at Le Moustier in southwest France by Otto Hauser. Astronomy * If its start and end are defined using mean solar time then due to the extreme length of day variation this is the longest year of the Julian calendar or Gregorian calendar, having a duration of 31622401.38 seconds of Terrestrial Time (or ephemeris time). * – Tunguska event in Siberia, an explosion believed to have been caused by the air burst of a large meteoroid or comet fragment at an altitude of above the Earth's surface. Chemistry * Kikunae Ikeda discovers monosodium glutamate, the chemical behind the taste of umami. * Heike Kamerlingh Onnes liquefies helium. Genetics * G. H. Hardy and Wilhelm Weinberg independently formulate the Hardy–Weinberg principle which states that both allele and genotype frequencies in a population remain in equilibrium unless ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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