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Meteors
A meteor, known colloquially as a shooting star, is a glowing streak of a small body (usually meteoroid) going through Earth's atmosphere, after being heated to incandescence by collisions with air molecules in the upper atmosphere, creating a streak of light via its rapid motion and sometimes also by shedding glowing material in its wake. Although a meteor may seem to be a few thousand feet from the Earth, meteors typically occur in the mesosphere at altitudes from . The root word ''meteor'' comes from the Greek ''meteōros'', meaning "high in the air". Millions of meteors occur in Earth's atmosphere daily. Most meteoroids that cause meteors are about the size of a grain of sand, i.e. they are usually millimeter-sized or smaller. Meteoroid sizes can be calculated from their mass and density which, in turn, can be estimated from the observed meteor trajectory in the upper atmosphere. Meteors may occur in showers, which arise when Earth passes through a stream of debris left ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Meteor Shower
A meteor shower is a celestial event in which a number of meteors are observed to radiate, or originate, from one point in the night sky. These meteors are caused by streams of cosmic debris called meteoroids entering Earth's atmosphere at extremely high speeds on parallel trajectories. Most meteors are smaller than a grain of sand, so almost all of them disintegrate and never hit the Earth's surface. Very intense or unusual meteor showers are known as meteor outbursts and meteor storms, which produce at least 1,000 meteors an hour, most notably from the Leonids. The Meteor Data Centre lists over 900 suspected meteor showers of which about 100 are well established. Several organizations point to viewing opportunities on the Internet. NASA maintains a daily map of active meteor showers. Historical developments A meteor shower in August 1583 was recorded in the Timbuktu manuscripts.Abraham, Curtis"Stars of the Sahara" ''New Scientist'', issue 2617,15 August 2007, page 39–41 I ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Leonids
The Leonids ( ) are a prolific annual meteor shower associated with the comet 55P/Tempel–Tuttle, Tempel–Tuttle, and are also known for their spectacular meteor storms that occur about every 33 years. The Leonids get their name from the location of their Radiant (meteor shower), radiant in the constellation Leo (constellation), Leo: the meteors appear to radiate from that point in the sky. The name is derived from Greek language, Greek and Latin, Latin with the prefix ''Leo-'' referring to the constellation and the suffix ''-ids'' signifying that the meteor shower is the offspring of, descendent of, the constellation Leo. Earth moves through meteoroid streams left from passages of a comet. The streams consist of solid particles, known as meteoroids, normally ejected by the comet as its frozen gases evaporate under the heat of the Sun once within Jupiter's orbit. Due to the Retrograde and prograde motion, retrograde orbit of 55P/Tempel–Tuttle, the Leonids are fast moving st ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Meteoroid
A meteoroid ( ) is a small rocky or metallic body in outer space. Meteoroids are distinguished as objects significantly smaller than ''asteroids'', ranging in size from grains to objects up to wide. Objects smaller than meteoroids are classified as ''micrometeoroids'' or ''space dust''. Many are fragments from comets or asteroids, whereas others are impact event, collision impact space debris, debris ejected from bodies such as the Moon or Mars. The visible passage of a meteoroid, comet, or asteroid atmospheric entry, entering Earth's atmosphere is called a meteor, and a series of many meteors appearing seconds or minutes apart and appearing to originate from the same fixed point in the sky is called a meteor shower. An estimated 25 million meteoroids, micrometeoroids and other space debris enter Earth's atmosphere each day, which results in an estimated 15,000 tonnes of that material entering the atmosphere each year. A ''meteorite'' is the remains of a meteoroid that has surv ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Radiant (meteor Shower)
The radiant or apparent radiant of a meteor shower is the celestial point in the sky from which (from the point of view of a terrestrial observer) the paths of meteors appear to originate. The Perseids, for example, are meteors which appear to come from a point within the constellation of Perseus. Meteor paths appear at random locations in the sky, but the apparent paths of two or more meteors from the same shower will diverge from the radiant. The radiant is the vanishing point of the meteor paths, which are parallel lines in three-dimensional space, as seen from the perspective of the observer, who views a two-dimensional projection against the sky. The geometric effect is identical to crepuscular rays, where parallel sunbeams appear to diverge. A meteor that does not point back to the known radiant for a given shower is known as a ''sporadic'' and is not considered part of that shower. Shower meteors may appear a short time before the radiant has risen in the observer's ea ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hubert Anson Newton
Hubert Anson Newton FRS HFRSE (19 March 1830 – 12 August 1896), usually cited as H. A. Newton, was an American astronomer and mathematician, noted for his research on meteors. Biography Newton was born at Sherburne, New York, and graduated from Yale in 1850 with a B.A. He continued his studies independently in New Haven and at home, due to the absence of Anthony Stanley, the primary professor of mathematics at Yale who was at the time dying of tuberculosis. Newton took up the position of tutor in January, 1853, a few months before Stanley's death, and served as the principal instructor of mathematics until 1855 when he was appointed professor of mathematics. He deferred taking up the appointment for one year, traveling to Europe to attend lectures by distinguished mathematicians. The Mathematics Genealogy Project lists his advisor as Michel Chasles, whose lectures on projective geometry he attended at the Sorbonne. Chasles' techniques had a significant impact on his subs ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
American Meteor Society
The American Meteor Society, Ltd. (AMS) is a non-profit scientific organization established to encourage and support the research activities of both amateur and professional astronomers who are interested in the field of meteor astronomy. Its affiliates observe, monitor, collect data on, study, and report on meteors, meteor showers, meteoric fireballs, and related meteoric phenomena. The society publishes observations and scientific interpretations quarterly in '' Meteor Trails, The Journal of American Meteor Society''. Once per year they give the '' American Meteor Society Award'' to a person who has contributed to research on meteors. They also provide an annual research grant to a student of SUNY-Geneseo who has contributed to meteor research or to the AMS. History The society was founded in 1911 by Charles P. Olivier of the Leander McCormick Observatory. The initial enrollment was fifteen members. These were recruited by Olivier by letter. The first paper based on the obs ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Meteorite
A meteorite is a rock (geology), rock that originated in outer space and has fallen to the surface of a planet or Natural satellite, moon. When the original object enters the atmosphere, various factors such as friction, pressure, and chemical interactions with the atmospheric gases cause it to heat up and radiate energy. It then becomes a meteor and forms a Meteoroid#Fireball, fireball, also known as a shooting star; astronomers call the brightest examples "Bolide#Astronomy, bolides". Once it settles on the larger body's surface, the meteor becomes a meteorite. Meteorites vary greatly in size. For geologists, a bolide is a meteorite large enough to create an impact crater. Meteorites that are recovered after being observed as they transit the atmosphere and impact event, impact Earth are called meteorite falls. All others are known as meteorite finds. Meteorites have traditionally been divided into three broad categories: stony meteorites that are rocks, mainly composed of sil ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Meteor Procession
A meteor procession occurs when an Earth-grazing meteor breaks apart, and the fragments travel across the sky in the same path. According to physicist Donald Olson, only four occurrences are known: * 18 August 1783 Great Meteor * 20 July 1860 Great Meteor; believed by Olson to be the event referred to in Walt Whitman's poem ''Year of Meteors, 1859–60'' * 21 December 1876 Great Meteor; sighted over Kansas, Missouri, Illinois, Indiana, Ohio, Pennsylvania * 9 February 1913 Great Meteor Procession; a chain of slow, large meteors moving from northwest to southeast, sighted over North America, particularly in Canada, the North Atlantic and the Tropical South Atlantic See also * * * * * * * * References External links Meteors, Meteoroids, and Meteorites Meteoroids {{meteoroid-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ram Pressure
Ram pressure is a pressure exerted on a body moving through a fluid medium, caused by relative bulk motion of the fluid rather than random thermal motion. It causes a drag (physics), drag force to be exerted on the body. Ram pressure is given in tensor form as :P_\text= \rho u_i u_j, where \rho is the density of the fluid; P_\text is the momentum flux per second in the i direction through a surface with normal in the j direction. u_i,u_j are the components of the fluid velocity in these directions. The total Cauchy stress tensor \sigma_ is the sum of this ram pressure and the isotropic thermal pressure (in the absence of viscosity). In the simple case when the relative velocity is normal to the surface, and momentum is fully transferred to the object, the ram pressure becomes :P_\text = 1/2 \rho u^2. Derivation The Lagrangian and Eulerian specification of the flow field, Eulerian form of the Cauchy momentum equation for a fluid is :\rho\frac = -\vec \nabla p - \rho(\vec u ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Bolide
A bolide is normally taken to mean an exceptionally bright meteor, but the term is subject to more than one definition, according to context. It may refer to any large Impact crater, crater-forming body, or to one that explodes in the atmosphere. It can be a synonym for a Meteoroid#Fireball, fireball, sometimes specific to those with an apparent magnitude of −4 or brighter. Definitions The word ''bolide'' (; from Italian language, Italian via Latin, ) may refer to somewhat different phenomena depending on the context in which the word appears, and readers may need to make inferences to determine which meaning is intended in a particular publication. An early usage occurs in ''Natural History (Pliny), Natural History'', where Pliny the Elder describes two types of prodigium, prodigies, "those which are called lampades and those which are called bolides". At least one of the prodigies described by Pliny (a "spark" that fell, grew to the "size of the moon", and "returned into the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Superbolide
A bolide is normally taken to mean an exceptionally bright meteor, but the term is subject to more than one definition, according to context. It may refer to any large crater-forming body, or to one that explodes in the atmosphere. It can be a synonym for a fireball, sometimes specific to those with an apparent magnitude of −4 or brighter. Definitions The word ''bolide'' (; from Italian via Latin, ) may refer to somewhat different phenomena depending on the context in which the word appears, and readers may need to make inferences to determine which meaning is intended in a particular publication. An early usage occurs in ''Natural History'', where Pliny the Elder describes two types of prodigies, "those which are called lampades and those which are called bolides". At least one of the prodigies described by Pliny (a "spark" that fell, grew to the "size of the moon", and "returned into the heavens") has been interpreted by astronomers as a bolide in the modern sense. His d ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mesosphere
The mesosphere (; ) is the third layer of the atmosphere, directly above the stratosphere and directly below the thermosphere. In the mesosphere, temperature decreases as altitude increases. This characteristic is used to define limits: it begins at the top of the stratosphere (sometimes called the stratopause), and ends at the mesopause, which is the coldest part of Earth's atmosphere, with temperatures below . The exact upper and lower boundaries of the mesosphere vary with latitude and with season (higher in winter and at the tropics, lower in summer and at the poles), but the lower boundary is usually located at altitudes from above sea level, and the upper boundary (the mesopause) is usually from . The stratosphere and mesosphere are sometimes collectively referred to as the "middle atmosphere", which spans altitudes approximately between above Earth's surface. The mesopause, at an altitude of , separates the mesosphere from the thermosphere—the second-outermost la ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
