81 résultats pour "solar"
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Estrella - ciencia y tecnologia.
Diagrama Hertzsprung-RussellLa posición en el diagrama H-R del punto que representa una estrella corresponde a su brillo y a su temperatura. Las estrellas de laizquierda del diagrama son azules porque son cálidas, y las de la derecha son rojas porque son frías. La banda diagonal que va desdeel extremo superior izquierdo al inferior derecho se denomina secuencia principal. Las estrellas del extremo superior derecho songigantes rojas, aunque son frías y rojas, son muy brillantes porque son muy gra...
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Tierra (planeta) - geografía.
químicos o estructurales que provocan discontinuidades. Los elementos menos pesados, como silicio, aluminio, calcio, potasio, sodio yoxígeno, componen la corteza exterior. Se puede considerar que la Tierra se divide en cinco partes: la primera, la atmósfera, es gaseosa; la segunda, la hidrosfera, es líquida; la tercera, cuarta y quinta, lalitosfera, el manto y el núcleo son sólidas. La atmósfera es la cubierta gaseosa que rodea el cuerpo sólido del planeta. Aunque tiene un grosor de más de 1.100...
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Tierra (planeta) - ciencia y tecnologia.
Desde los comienzos de la historia de nuestro planeta, éste está compuesto de diversas capas que se formaron mientras losmateriales pesados gravitaban hacia el centro y los más ligeros salían a la superficie. Entre algunas de las capas se producen cambiosquímicos o estructurales que provocan discontinuidades. Los elementos menos pesados, como silicio, aluminio, calcio, potasio, sodio yoxígeno, componen la corteza exterior.© Microsoft Corporation. Reservados todos los derechos. Se puede considera...
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Sistema de Posicionamiento Global
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INTRODUCCIÓN
Sistema de Posicionamiento Global
Puesta en órbita de un satélite Navstar de Sistema de Posicionamiento Global (GPS) mediante cohetes Delta.
satélites desde Cabo Cañaveral, en Florida, Estados Unidos. Los satélites GPS se desplazan en órbitas circulares a 17.440 km de altitud, invirtiendo 12 horas en cada una delas órbitas. Éstas tienen una inclinación de 55° para asegurar la cobertura de las regiones polares. La energía la proporcionan células solares, por lo que los satélites seorientan continuamente dirigiendo los paneles solares hacia el Sol y las antenas hacia la Tierra. Cada satélite cuenta con cuatro relojes atómicos. La divis...
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Russischer Film.
war, und der Forderung nach systemkonformer Durchschnittsware. Die Zahl international renommierter sowjetischer Regisseure blieb insgesamt spärlich, und ihr WortführerTarkowskij, der sich mit der Stanislaw-Lem-Verfilmung Solaris (1972; Solaris ) und Stalker (1979; Der Stalker ) unter die weltweit besten seines Faches eingereiht hatte, kehrte nach den Dreharbeiten zu Nostalghia in Italien (1983; Nostalghia ) nicht mehr in die UdSSR zurück. Zwar entstanden auch kritische Bestandsaufnahmen...
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Contaminación atmosférica - ciencias de la naturaleza.
nitrógeno, y de un 30 a un 40% de las partículas en suspensión emitidos a la atmósfera en Estados Unidos proceden de las centrales eléctricas que queman combustiblesfósiles, las calderas industriales y las calefacciones. Un 80% del monóxido de carbono y un 40% de los óxidos de nitrógeno e hidrocarburos emitidos proceden de lacombustión de la gasolina y el gasóleo en los motores de los coches y camiones. Otras importantes fuentes de contaminación son la siderurgia y las acerías, las fundicionesde...
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Galaxy - astronomy.
Astronomers have obtained images of young galaxies using the Keck Telescope in Hawaii and the Hubble Space Telescope, which resides in an orbit high above Earth’satmosphere and thus avoids atmospheric interference. Photos from the HST show galaxies that are as far as 13 billion light-years away from Earth, which means theyformed soon after the universe formed about 13.7 billion years ago. The galaxies appear to be spherical in shape, and may be early precursors of elliptical and spiralgalaxies....
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Ice Ages.
B Future Ice Ages The record of previous glacial activity is the best indicator for future ice ages. Scientists examine the evidence for the numerous 100,000-year glacial-interglacial cycleswithin the present ice age to attempt a forecast of future ice ages. Since all previous ice ages lasted tens of millions of years, our present ice age will likely continue fora considerable amount of time. Each glaciation begins slowly and may take 80,000 years or more to reach its maximum extent. A rapid me...
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Metabolismo - ciencias de la naturaleza.
Tanto los sistemas mecánicos como los orgánicos desprenden también grandes cantidades de energía calorífica y proporciones pequeñas de energía útil. El músculo animalrinde casi una caloría útil por cada cuatro desprendidas en forma de calor. Pero, en los organismos animales el calor no se desperdicia por completo, pues es muy necesario—sobre todo en los animales de sangre caliente— para conservar la temperatura del cuerpo y para inducir las reacciones metabólicas, que a temperaturas más bajas se...
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Arctic - Geography.
The Arctic is not a frozen desert devoid of life on land or sea, even during the cold, dark winter months. Spring brings a phenomenal resurgence of plant and animal life.Low temperatures are not always the critical element—moisture, the type of soil, and available solar energy are also extremely important. Some animals adapt well toArctic conditions; for instance, a number of species of mammals and birds carry additional insulation, such as fat, in cold months. Arctic summers with extended dayli...
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Relativity
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INTRODUCTION
Albert Einstein
In 1905 German-born American physicist Albert Einstein published his first paper outlining the theory of relativity.
in calculating very large distances or very large aggregations of matter. As the quantum theory applies to the very small, so the relativity theory applies to the verylarge. Until 1887 no flaw had appeared in the rapidly developing body of classical physics. In that year, the Michelson-Morley experiment, named after the American physicistAlbert Michelson and the American chemist Edward Williams Morley, was performed. It was an attempt to determine the rate of the motion of the earth through t...
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Carbon - chemistry.
Graphite is black and slippery and conducts electricity. In graphite, the atoms form planar, or flat, layers. Each layer is made up of rings containing six carbon atoms.The rings are linked to each other in a structure that resembles the hexagonal mesh of chicken wire. Each atom has three sigma bonds (with 120° between any two ofthe bonds) and belongs to three neighboring rings. The fourth electron of each atom becomes part of an extensive pi bond system. Graphite conducts electricity,because th...
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Gravitation
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INTRODUCTION
Gravitation, the force of attraction between all objects that tends to pull them toward one another.
precise observations possible, and Galileo was one of the first to use a telescope to study astronomy. In 1609 Galileo observed that moons orbited the planet Jupiter, afact that could not reasonably fit into an earth-centered model of the heavens. The new heliocentric theory changed scientists' views about the earth's place in the universe and opened the way for new ideas about the forces behind planetarymotion. However, it was not until the late 17th century that Isaac Newton developed a theory...
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Gravitation - astronomy.
precise observations possible, and Galileo was one of the first to use a telescope to study astronomy. In 1609 Galileo observed that moons orbited the planet Jupiter, afact that could not reasonably fit into an earth-centered model of the heavens. The new heliocentric theory changed scientists' views about the earth's place in the universe and opened the way for new ideas about the forces behind planetarymotion. However, it was not until the late 17th century that Isaac Newton developed a theory...
- solar system
- Los planetas - (exposé gratuit en espagnol).
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- El Sol - (exposé gratuit en espagnol).
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Ulysses (spacecraft) - astronomy.
Ulysses was also used to study comet Hale-Bopp, which was first seen in 1995. Hale-Bopp travels an unusual path at a large angle to the ecliptic, and the trajectory ofUlysses was well suited to capture images of Hale-Bopp as it made its way around the Sun. Astronomers paid particular attention to Hale-Bopp’s plasma tail—a plume ofionized, or electrically charged, gas within the main tail that streams away from the comet when it approaches within about 1.5 AU from the Sun. They found that theplas...
- Voile Solaire
- Las energías renovables - (exposé gratuit en espagnol).
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Calendar.
on lunar months of 29 days alternating with 30 days. An extra month is intercalated every 3 years, based on a cycle of 19 years. Dates of the Jewish calendar aredesignated AM (Latin anno mundi, ”the year of the world”) and BCE (before the common era). Another major religious calendar is the Islamic calendar, a lunar one used in most Muslim countries. It is reckoned from AD 622, the day after the Hegira, or emigration of Muhammad from Mecca to Medina. The Islamic year consists of 12 lunar mo...
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Astronomy - astronomy.
Telescopes may use either lenses or mirrors to gather visible light, permitting direct observation or photographic recording of distant objects. Those that use lenses arecalled refracting telescopes, since they use the property of refraction, or bending, of light ( see Optics: Reflection and Refraction ). The largest refracting telescope is the 40-in (1-m) telescope at the Yerkes Observatory in Williams Bay, Wisconsin, founded in the late 19th century. Lenses bend different colors of light by d...
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Previsión meteorológica - geografía.
Meteorología con satélitesLa mayoría de los servicios meteorológicos utilizan información de los satélites para elaborar sus previsiones. Fotografías como éstadel huracán Gloria revelan patrones y movimientos que suministran pistas sobre la evolución de la tormenta. El clima es vigilado yfotografiado de forma continua por los satélites en todo el mundo, pero sigue siendo difícil predecir el tiempo porque hay muchasvariables implicadas. Los sensores infrarrojos ayudan a los meteorólogos en la int...
- Skylab - astronomy.
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Earth (planet).
Milky Way to complete one revolution around the Galaxy’s center. Earth’s axis of rotation is inclined (tilted) 23.5° relative to its plane of revolution around the Sun. This inclination of the axis creates the seasons and causes the height of the Sun in the sky at noon to increase and decrease as the seasons change. The Northern Hemisphere receives the most energy from the Sun when it is tiltedtoward the Sun. This orientation corresponds to summer in the Northern Hemisphere and winter in the S...
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Earth (planet) - astronomy.
Milky Way to complete one revolution around the Galaxy’s center. Earth’s axis of rotation is inclined (tilted) 23.5° relative to its plane of revolution around the Sun. This inclination of the axis creates the seasons and causes the height of the Sun in the sky at noon to increase and decrease as the seasons change. The Northern Hemisphere receives the most energy from the Sun when it is tiltedtoward the Sun. This orientation corresponds to summer in the Northern Hemisphere and winter in the S...
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Space Exploration - astronomy.
to produce 250,000 newtons (56,000 lb) of thrust. The Germans launched thousands of V-2s carrying explosives against targets in Britain and The Netherlands. Whilethey did not prove to be an effective weapon, V-2s did become the first human-made objects to reach altitudes above 80 km (50 mi)—the height at which outer spaceis considered to begin—before falling back to Earth. The V-2 inaugurated the era of modern rocketry. A2 Early Artificial Satellites During the years following World War II, the...
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Fotosíntesis - ciencias de la naturaleza.
Cloroplastos de raíz de cebollaLos cloroplastos son diminutas estructuras esféricas verdes esenciales para la fotosíntesis. La molécula de clorofila, un compuestoorgánico muy complejo de magnesio, carbono e hidrógeno, regula la absorción de las porciones roja, violeta y azul del espectrovisible.Richard Kirde/Oxford Scientific Films La primera etapa de la fotosíntesis es la absorción de luz por los pigmentos. La clorofila es el más importante de éstos, y es esencial para el proceso. Captura la lu...
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La science-fiction est un produit culturel des sociétés industrielles.
capitalisme désespéré, les Soviétiques se mirent à la traduire. Cela stimula des auteurs tels qu'Alexandre Karantzeff et Nemtsov. Le genre se développa également en Allemagne (Freder Van Holk, Richard Koch) ainsi qu'en Roumanie et en Chine. Le format de la nouvelle, bien adapté aux magazines, s'est largement développé avec de brillants auteurs comme Damon Knight, Richard Matheson, Frederic Brown ou encore James Graham Ballard. De plus en plus estimée par le monde littéraire,...
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NASA - astronomy.
Challenger shuttle after launch in 1986 and the Columbia shuttle during reentry in 2003, killing both crews. Investigations traced the accidents to design flaws and tomanagement problems. Both accidents led to design and procedure changes, and to a temporary stoppage of shuttle flights. Following the Columbia disaster, NASA alsoannounced plans to retire the shuttle in 2010, after completion of the International Space Station (ISS), a human orbital research facility. The Constellation program is...
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"A Modest Proposal" - anthology.
I SHALL now therefore humbly propose my own Thoughts; which I hope will not be liable to the least Objection. I HAVE been assured by a very knowing American of my Acquaintance in London; that a young healthy Child, well nursed, is, at a Year old, a most delicious, nourishing, and wholesome Food; whether Stewed, Roasted, Baked, or Boiled; and, I make no doubt, that it will equally serve in a Fricasie, or Ragoust. I DO therefore humbly offer it to publick Consideration, that of...