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Comet Arend–Roland
Comet Arend–Roland was discovered on November 8, 1956 by Belgian astronomers Sylvain Arend and Georges Roland on photographic plates. As the eighth comet found in 1956, it was named Arend–Roland 1956h after its discoverers. Because it was the third comet to pass through perihelion during 1957, it was then renamed 1957 III. Finally, it received the standard IAU designation C/1956 R1 (Arend–Roland), with the "C/" indicating that it was a non-periodic comet and the "R1" showing that it was the first comet reported as discovered in the half-month designated by "R". The last is equivalent to the period September 1–15. Observations In November 1956, a double astrograph at the Uccle Observatory in Brussels was being used for routine investigation of minor planets. On November 8, 1956, the Belgian astronomers Sylvain Arend and Georges Roland discovered a comet on their photographic plates. At that time the comet was at visual magnitude 10, with a strong central condensation and a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Comet Arend-Roland On April 27 By Palomar
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 milli ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Visual Magnitude
Apparent magnitude () is a measure of the brightness of a star or other astronomical object observed from Earth. An object's apparent magnitude depends on its intrinsic luminosity, its distance from Earth, and any extinction of the object's light caused by interstellar dust along the line of sight to the observer. The word ''magnitude'' in astronomy, unless stated otherwise, usually refers to a celestial object's apparent magnitude. The magnitude scale dates back to the ancient Roman astronomer Claudius Ptolemy, whose star catalog listed stars from 1st magnitude (brightest) to 6th magnitude (dimmest). The modern scale was mathematically defined in a way to closely match this historical system. The scale is reverse logarithmic: the brighter an object is, the lower its magnitude number. A difference of 1.0 in magnitude corresponds to a brightness ratio of \sqrt /math>, or about 2.512. For example, a star of magnitude 2.0 is 2.512 times as bright as a star of magnitude 3.0, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Orbital Eccentricity
In astrodynamics, the orbital eccentricity of an astronomical object is a dimensionless parameter that determines the amount by which its orbit around another body deviates from a perfect circle. A value of 0 is a circular orbit, values between 0 and 1 form an elliptic orbit, 1 is a parabolic escape orbit (or capture orbit), and greater than 1 is a hyperbola. The term derives its name from the parameters of conic sections, as every Kepler orbit is a conic section. It is normally used for the isolated two-body problem, but extensions exist for objects following a rosette orbit through the Galaxy. Definition In a two-body problem with inverse-square-law force, every orbit is a Kepler orbit. The eccentricity of this Kepler orbit is a non-negative number that defines its shape. The eccentricity may take the following values: * circular orbit: ''e'' = 0 * elliptic orbit: 0 < ''e'' < 1 * [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Semi-major Axis
In geometry, the major axis of an ellipse is its longest diameter: a line segment that runs through the center and both foci, with ends at the two most widely separated points of the perimeter. The semi-major axis (major semiaxis) is the longest semidiameter or one half of the major axis, and thus runs from the centre, through a focus, and to the perimeter. The semi-minor axis (minor semiaxis) of an ellipse or hyperbola is a line segment that is at right angles with the semi-major axis and has one end at the center of the conic section. For the special case of a circle, the lengths of the semi-axes are both equal to the radius of the circle. The length of the semi-major axis of an ellipse is related to the semi-minor axis's length through the eccentricity and the semi-latus rectum \ell, as follows: The semi-major axis of a hyperbola is, depending on the convention, plus or minus one half of the distance between the two branches. Thus it is the distance from the center ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Perihelion
An apsis (; ) is the farthest or nearest point in the orbit of a planetary body about its primary body. For example, the apsides of the Earth are called the aphelion and perihelion. General description There are two apsides in any elliptic orbit. The name for each apsis is created from the prefixes ''ap-'', ''apo-'' (), or ''peri-'' (), each referring to the farthest and closest point to the primary body the affixing necessary suffix that describes the primary body in the orbit. In this case, the suffix for Earth is ''-gee'', so the apsides' names are ''apogee'' and ''perigee''. For the Sun, its suffix is ''-helion'', so the names are ''aphelion'' and ''perihelion''. According to Newton's laws of motion, all periodic orbits are ellipses. The barycenter of the two bodies may lie well within the bigger body—e.g., the Earth–Moon barycenter is about 75% of the way from Earth's center to its surface. If, compared to the larger mass, the smaller mass is negligible (e.g., f ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Apsis
An apsis (; ) is the farthest or nearest point in the orbit of a planetary body about its primary body. For example, the apsides of the Earth are called the aphelion and perihelion. General description There are two apsides in any elliptic orbit. The name for each apsis is created from the prefixes ''ap-'', ''apo-'' (), or ''peri-'' (), each referring to the farthest and closest point to the primary body the affixing necessary suffix that describes the primary body in the orbit. In this case, the suffix for Earth is ''-gee'', so the apsides' names are ''apogee'' and ''perigee''. For the Sun, its suffix is ''-helion'', so the names are ''aphelion'' and ''perihelion''. According to Newton's laws of motion, all periodic orbits are ellipses. The barycenter of the two bodies may lie well within the bigger body—e.g., the Earth–Moon barycenter is about 75% of the way from Earth's center to its surface. If, compared to the larger mass, the smaller mass is negligible (e.g., f ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hyperbola
In mathematics, a hyperbola (; pl. hyperbolas or hyperbolae ; adj. hyperbolic ) is a type of smooth curve lying in a plane, defined by its geometric properties or by equations for which it is the solution set. A hyperbola has two pieces, called connected components or branches, that are mirror images of each other and resemble two infinite bows. The hyperbola is one of the three kinds of conic section, formed by the intersection of a plane and a double cone. (The other conic sections are the parabola and the ellipse. A circle is a special case of an ellipse.) If the plane intersects both halves of the double cone but does not pass through the apex of the cones, then the conic is a hyperbola. Hyperbolas arise in many ways: * as the curve representing the reciprocal function y(x) = 1/x in the Cartesian plane, * as the path followed by the shadow of the tip of a sundial, * as the shape of an open orbit (as distinct from a closed elliptical orbit), such as the orbit of a s ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cosmos (book)
''Cosmos'' is a popular science book written by astronomer and Pulitzer Prize-winning author Carl Sagan. It was published in 1980 as a companion piece to the PBS mini-series Cosmos: A Personal Voyage with which it was co-developed and intended to compliment. Each of the book’s 13 illustrated chapters corresponds to one of the 13 episodes of the television series. Just a few of the ideas explored in Cosmos include the history and mutual development of science and civilization, the nature of the Universe, human and robotic space exploration, the inner workings of the cell and the DNA that controls it, and the dangers and future implications of nuclear war. One of Sagan's main purposes for both the book and the television series was to explain complex scientific ideas in a way that anyone interested in learning can understand. Sagan also believed the television was one of the greatest teaching tools ever invented, so he wished to capitalize on his chance to educate the world. Spu ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Carl Sagan
Carl Edward Sagan (; ; November 9, 1934December 20, 1996) was an American astronomer, planetary scientist, cosmologist, astrophysicist, astrobiologist, author, and science communicator. His best known scientific contribution is research on extraterrestrial life, including experimental demonstration of the production of amino acids from basic chemicals by radiation. Sagan assembled the first physical messages sent into space, the Pioneer plaque and the Voyager Golden Record, universal messages that could potentially be understood by any extraterrestrial intelligence that might find them. Sagan argued the hypothesis, accepted since, that the high surface temperatures of Venus can be attributed to, and calculated using, the greenhouse effect.Extract of page 14 Initially an assistant professor at [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
The Sky At Night
''The Sky at Night'' is a monthly documentary television programme on astronomy produced by the BBC. The show had the same permanent presenter, Sir Patrick Moore, from its first broadcast on 24 April 1957 until 7 January 2013. The latter date was a posthumous broadcast, following Moore's death on 9 December 2012. This made it the longest-running programme with the same presenter in television history. Many early episodes are missing, either because the tapes were wiped or thrown out, or because the episode was broadcast live and never recorded in the first place. Beginning with the 3 February 2013 edition, the show was co-presented by Lucie Green and Chris Lintott. Since December 2013 Maggie Aderin-Pocock has also been a presenter. Pete Lawrence has presented an observing section on the programme since 2004 as well as producing an online monthly online star Guide on the BBC Sky at Night webpage. The programme's opening and closing theme music is "At the Castle Gate", from th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Comet Kohoutek
Comet Kohoutek ( formally designated C/1973 E1 and formerly as 1973 XII and 1973f) is a comet that passed close to the Sun towards the end of 1973. Early predictions of the comet's peak brightness suggested that it had the potential to become one of the brightest comets of the 20th century, capturing the attention of the wider public and the press and earning the comet the moniker of "Comet of the Century". Although Kohoutek became rather bright, the comet was ultimately far dimmer than the optimistic projections: its apparent magnitude peaked at only –3 (as opposed to predictions of roughly magnitude –10) and it was visible for only a short period, quickly dimming below naked-eye visibility by the end of January 1974. The comet was discovered by and named after Luboš Kohoutek at the Hamburg Observatory on 18 March 1973; Kohoutek had been searching for Biela's Comet and had fortuitously discovered his eponymous comet while reviewing photographic plates for a differ ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Antitail
An antitail is a spike projecting from a comet's coma which seems to go towards the Sun, and thus geometrically opposite to the other tails: the ''ion tail'' and the ''dust tail''. However, this phenomenon is an optical illusion that is seen from the Earth. The antitail consists of larger dust particles, which are less affected by the Sun's radiation pressure and tend to remain roughly in the comet's orbital plane and eventually form a disc along the comet's orbit due to the ejection speed of the particles from the comet's surface. As Earth passes through the comet's orbital plane, this disc is seen side on, and appears as the characteristic spike. The other side of the disc can sometimes be seen, though it tends to be lost in the dust tail. The antitail is therefore normally visible for a brief interval only when Earth passes through the comet's orbital plane. Most comets do not develop sufficiently for an antitail to become visible, but notable comets that did display antita ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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