File:Comet-Hale-Bopp-29-03-1997 hires adj.jpg. Tornado. Violently rotating column of air in contact with both the earth's surface and a cumulonimbus cloud A tornado is a violently rotating column of air that is in contact with both the surface of the Earth and a cumulonimbus cloud or, in rare cases, the base of a cumulus cloud. It is often referred to as a twister, whirlwind or cyclone,[1] although the word cyclone is used in meteorology to name a weather system with a low-pressure area in the center around which, from an observer looking down toward the surface of the earth, winds blow counterclockwise in the Northern Hemisphere and clockwise in the Southern.[2] Tornadoes come in many shapes and sizes, and they are often visible in the form of a condensation funnel originating from the base of a cumulonimbus cloud, with a cloud of rotating debris and dust beneath it. Most tornadoes have wind speeds less than 110 miles per hour (180 km/h), are about 250 feet (80 m) across, and travel a few miles (several kilometers) before dissipating.
Types. Untitled. Synapse. Structure connecting neurons in the nervous system In the nervous system, a synapse[1] is a structure that permits a neuron (or nerve cell) to pass an electrical or chemical signal to another neuron or to the target effector cell. History[edit] However, while the synaptic gap remained a theoretical construct, and was sometimes reported as a discontinuity between contiguous axonal terminations and dendrites or cell bodies, histological methods using the best light microscopes of the day could not visually resolve their separation which is now known to be about 20nm. It needed the electron microscope in the 1950s to show the finer structure of the synapse with its separate, parallel pre- and postsynaptic membranes and processes, and the cleft between the two.[8][9][10] Types of synapses[edit] Synaptic communication is distinct from an ephaptic coupling, in which communication between neurons occurs via indirect electric fields.
Types of interfaces[edit] Role in memory[edit] Study models[edit] Speed of sound. Speed of sound wave through elastic medium The speed of sound in an ideal gas depends only on its temperature and composition. The speed has a weak dependence on frequency and pressure in ordinary air, deviating slightly from ideal behavior. In colloquial speech, speed of sound refers to the speed of sound waves in air. However, the speed of sound varies from substance to substance: typically, sound travels most slowly in gases, faster in liquids, and fastest in solids.
For example, while sound travels at 343 m/s in air, it travels at 1,481 m/s in water (almost 4.3 times as fast) and at 5,120 m/s in iron (almost 15 times as fast). In fluid dynamics, the speed of sound in a fluid medium (gas or liquid) is used as a relative measure for the speed of an object moving through the medium. History[edit] Sir Isaac Newton's 1687 Principia includes a computation of the speed of sound in air as 979 feet per second (298 m/s). Derham used a telescope from the tower of the church of St. Note that . . File:FA-18 Hornet breaking sound barrier (7 July 1999) - filtered.jpg. Moon. Natural satellite orbiting the Earth Both the Moon's prominence in Earth's sky and its regular cycle of phases have provided cultural references and influences for human societies throughout history. Such influences can be found in language, calendar systems, art, and mythology. The first artificial object to reach the Moon was the Soviet Union's uncrewed Luna 2 spacecraft in 1959; this was followed by the first successful soft landing by Luna 9 in 1966.
The only human lunar missions to date have been those of the United States' Apollo program, which landed twelve men on the surface between 1969 and 1972. These and later uncrewed missions returned lunar rocks that have been used to develop a detailed geological understanding of the Moon's origins, internal structure, and subsequent history. The Moon is the only celestial body visited by humans. Names and etymology The usual English adjective pertaining to the Moon is "lunar", derived from the Latin word for the Moon, lūna. Natural history. Untitled. Star. Large self-illuminated object in space A star's life begins with the gravitational collapse of a gaseous nebula of material largely comprising hydrogen, helium, and trace heavier elements. Its total mass mainly determines its evolution and eventual fate. A star shines for most of its active life due to the thermonuclear fusion of hydrogen into helium in its core.
This process releases energy that traverses the star's interior and radiates into outer space. At the end of a star's lifetime, its core becomes a stellar remnant: a white dwarf, a neutron star, or—if it is sufficiently massive—a black hole. Stars can form orbital systems with other astronomical objects, as in planetary systems and star systems with two or more stars. When two such stars orbit closely, their gravitational interaction can significantly impact their evolution. Etymology Observation history Historically, stars have been important to civilizations throughout the world. Designations Units of measurement Star formation Age.
File:The Sun by the Atmospheric Imaging Assembly of NASA's Solar Dynamics Observatory - 20100819.jpg. Mars. Fourth planet from the Sun Geologically, Mars is fairly active, with dust devils sweeping across the landscape and marsquakes (Martian analog to earthquakes) trembling underneath the ground. The surface of Mars hosts a large shield volcano (Olympus Mons) and one of the largest canyons in the Solar System (Valles Marineris).
Mars's significant orbital eccentricity and axial tilt cause large seasonal changes to the polar ice caps' coverage and temperature swings between −110 °C (−166 °F) to 35 °C (95 °F) on the surface. A Martian solar day (sol) is equal to 24.5 hours and a Martian solar year is equal to 1.88 Earth years. Mars is among the brightest objects in Earth's sky, and thus has been known from ancient times. Its high-contrast albedo features make it a common subject for viewing with a telescope. Natural history After the formation of the planets, all were subjected to the so-called "Late Heavy Bombardment". Geological activity is still taking place on Mars. Physical characteristics. 2MarsOrbit-MarsEarth. 433 Eros. 433 Eros is an S-type near-Earth asteroid approximately 34.4×11.2×11.2 kilometres (21.4×7.0×7.0 mi) in size, the second-largest near-Earth asteroid after 1036 Ganymed.
It was discovered in 1898 and was the first near-Earth asteroid discovered. It was the first asteroid orbited by an Earth probe (in 2000). It belongs to the Amor group. The NEAR Shoemaker probe visited Eros twice, first with a 1998 flyby, and then by orbiting it in 2000 when it extensively photographed its surface. On February 12, 2001, at the end of its mission, it landed on the asteroid's surface using its maneuvering jets. History[edit] Animation of the rotation of Eros. View from one end of Eros across the gouge on its side towards the opposite end. At 4.8 km (3.0 mi) across, the crater Psyche is Eros's second largest. Regolith of Eros, seen during NEAR's descent; area shown is about 12 meters (40 feet) across Orbital diagram of Eros with locations on May 7, 2013 Discovery[edit] Later studies[edit] Name[edit] See also[edit] Ficheiro:433eros.jpg. Orbital speed. The orbital speed at any position in the orbit can be computed from the distance to the central body at that position, and the specific orbital energy, which is independent of position: the kinetic energy is the total energy minus the potential energy.
Radial trajectories[edit] In the case of radial motion:[citation needed] Transverse orbital speed[edit] The transverse orbital speed is inversely proportional to the distance to the central body because of the law of conservation of angular momentum, or equivalently, Kepler's second law. This law implies that the body moves slower near its apoapsis than near its periapsis, because at the smaller distance along the arc it needs to trace to cover the same area. Mean orbital speed[edit] where v is the orbital velocity, a is the length of the semimajor axis, T is the orbital period, and μ=GM is the standard gravitational parameter.
Taking into account the mass of the orbiting body, or assuming r equal to the body's radius Precise orbital speed[edit] File:Full Sunburst over Earth.JPG. Helios (spacecraft) Helios-A and Helios-B (also known as Helios 1 and Helios 2), are a pair of probes launched into heliocentric orbit for the purpose of studying solar processes. A joint venture of the Federal Republic of Germany (West Germany) and NASA, the probes were launched from Cape Canaveral, Florida, on Dec. 10, 1974, and Jan. 15, 1976, respectively. Ficheiro:Titan 3E Centaur with Helios 1.jpg. Star. Ficheiro:Achernar.jpg. Sol. Origem: Wikipédia, a enciclopédia livre. O Sol (do latim sol, solis[12] ) é a estrela central do Sistema Solar. Todos os outros corpos do Sistema Solar, como planetas, planetas anões, asteroides, cometas e poeira, bem como todos os satélites associados a estes corpos, giram ao seu redor. Responsável por 99,86% da massa do Sistema Solar, o Sol possui uma massa 332 900 vezes maior que a da Terra, e um volume 1 300 000 vezes maior que o do nosso planeta.[13] É composto primariamente de hidrogênio (74% de sua massa, ou 92% de seu volume) e hélio (24% da massa solar, 7% do volume solar), com traços de outros elementos, incluindo ferro, níquel, oxigênio, silício, enxofre, magnésio, néon, cálcio e crômio.[17] A coroa solar expande-se continuamente no espaço, criando o vento solar, uma corrente de partículas carregadas que estende-se até a heliopausa, a cerca de 100 UA do Sol.
Estrutura solar[editar | editar código-fonte] Uma ilustração da estrutura do Sol: Núcleo[editar | editar código-fonte] Notas. File:Sun in orbit around Galactic Centre.gif. Via Láctea possui velocidade de rotação de 240 km/s. Sistema Solar leva 200 milhões de ano para dar uma volta completa (Fonte da imagem: NAOJ) Uma equipe de astrônomos liderada pelo professor Mareki Honma, no Observatório Nacional Astronômico do Japão (NAOJ), determinou com mais precisão algumas medidas referentes à nossa galáxia. Usando radiotelescópios bastante avançados, os novos cálculos garantem que a Via Láctea tem mais matéria escura do que imaginávamos. De acordo com o press release liberado pela organização, as novas descobertas dizem que a distância do Sol até o centro da galáxia é de 26,1 mil anos-luz. Além disso, a velocidade de rotação da Via Láctea na região do nosso sistema solar é de 240 km/s, velocidade ligeiramente maior do que a considerada pela União Astronômica Internacional (IAU) desde 1985 (220 km/s).
Com base nisso, os cientistas também estimaram uma nova massa para a Via Láctea, já que essa propriedade influencia no cálculo da velocidade. Milky Way. Galaxy containing the Solar System The Milky Way is a barred spiral galaxy with an estimated D25 isophotal diameter of 26.8 ± 1.1 kiloparsecs (87,400 ± 3,590 light-years),[8] but only about 1,000 light years thick at the spiral arms (more at the bulge).
Recent simulations suggest that a dark matter area, also containing some visible stars, may extend up to a diameter of almost 2 million light-years (613 kpc).[28][29] The Milky Way has several satellite galaxies and is part of the Local Group of galaxies, which form part of the Virgo Supercluster, which is itself a component of the Laniakea Supercluster.[30][31] Etymology and mythology[edit] The Origin of the Milky Way by Tintoretto (circa 1575–1580) In Greek mythology, Zeus places his son born by a mortal woman, the infant Heracles, on Hera's breast while she is asleep so the baby will drink her divine milk and thus become immortal.
Appearance[edit] The Milky Way viewed at different wavelengths Astronomical history[edit] Astrography[edit] Untitled. Solar wind. History[edit] The existence of a continuous stream of particles flowing outward from the Sun was first suggested by British astronomer Richard C. Carrington. In 1859, Carrington and Richard Hodgson independently made the first observation of what would later be called a solar flare. This is a sudden outburst of energy from the Sun's atmosphere. On the following day, a geomagnetic storm was observed, and Carrington suspected that there might be a connection. George FitzGerald later suggested that matter was being regularly accelerated away from the Sun and was reaching the Earth after several days.[1] Laboratory simulation of the magnetosphere's influence on the Solar Wind; these auroral-like Birkeland currents were created in a terrella, a magnetised anode globe in an evacuated chamber.
Opposition to Parker's hypothesis on the solar wind was strong. Emission[edit] The Sun's corona, or extended outer layer, is a region of plasma that is heated to over a million degrees Celsius. File:Structure of the magnetosphere mod PT.png. Velocidade da luz. Origem: Wikipédia, a enciclopédia livre. Os raios demonstram a diferença entre a velocidade da luz e a velocidade do som: primeiro vem a luz (relâmpago) e depois o som (trovão).
A unidade fundamental do Sistema Internacional de Unidades (SI) para comprimentos, o metro, é definida desde 21 de outubro de 1983 como a distância que a luz viaja no vácuo em 1/299 792 458 do segundo. Sendo assim, a definição do metro passou a ser dependente da velocidade da luz, numa inversão do que havia anteriormente. Assim, qualquer mudança na definição do correspondente numérico da velocidade da luz modificaria a definição do metro, ao passo que eventuais novos cálculos da velocidade da luz poderiam, ao invés de mudar o valor numérico do "c", modificar a medida do metro. Valor numérico, notação e unidades[editar | editar código-fonte] A velocidade da luz no vácuo é geralmente denotada por c, de "constante" ou da palavra latina celeritas (que significa "rapidez").
História[editar | editar código-fonte] Mas: De onde vem a energia vital que anima os seres na Terra? | Yahoo Respostas. Oi amigo, Nota; Desculpe se repito alguns links que talvez já lhe tenha passado anteriormente, mas faço isso como força de expressão e também em respeito e consideração ao público que visita este espaço YR Ok? Bom…, Estamos nesse novo século iniciando o descobrimento de que o universo possui um papel muito mais complexo do que jamais poderia se esperar no tocante à vida. Nessa nova era a ciência começa a perceber de que tudo o que se pensou até agora sobre vida talvez tenha que ser reformulado. A ciência começa a perceber que talvez a filosofia hindu e budista estejam certas quando apontam para um universo vivo, mental e autoconsciente. Teorias de vida eterna num universo autoconsciente começam a aflorar. A teoria de que a vida vem da própria vida onde a morte seria mais uma forma de superação numa transformação evolutiva da própria vida.