File:Comet-Hale-Bopp-29-03-1997 hires adj.jpg. Tornado. A tornado is a violently rotating column of air that spins while in contact with both the surface of the Earth and a cumulonimbus cloud or, in rare cases, the base of a cumulus cloud. They are often referred to as twisters, whirlwinds or cyclones, although the word cyclone is used in meteorology to name any closed low pressure circulation. Tornadoes come in many shapes and sizes, but they are typically in the form of a visible condensation funnel originating from the base of a huge storm cloud, whose narrow end touches the earth and is often encircled by a basal cloud of debris and dust. 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. The most extreme tornadoes can attain wind speeds of more than 300 miles per hour (480 km/h), are more than two miles (3 km) in diameter, and stay on the ground for dozens of miles (more than 100 km). Etymology Definitions.
Untitled. Synapse. In the nervous system, a synapse 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. Chemical or electrical There are two fundamentally different types of synapses: In a chemical synapse, electrical activity in the presynaptic neuron is converted (via the activation of voltage-gated calcium channels) into the release of a chemical called a neurotransmitter that binds to receptors located in the plasma membrane of the postsynaptic cell. The neurotransmitter may initiate an electrical response or a secondary messenger pathway that may either excite or inhibit the postsynaptic neuron.
Chemical synapses can be classified according to the neurotransmitter released: glutamatergic (often excitatory), GABAergic (often inhibitory), cholinergic (e.g. vertebrate neuromuscular junction), and adrenergic (releasing norepinephrine). Types of interfaces Different types of synapses Role in memory Speed of sound. 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 common everyday speech, speed of sound refers to the speed of sound waves in air. However, the speed of sound varies from substance to substance: sound travels most slowly in gases; it travels faster in liquids; and faster still in solids. For example, (as noted above), sound travels at 343 m/s in air; it travels at 1,484 m/s in water (4.3 times as fast as in air); and at 5,120 m/s in iron.
In an exceptionally stiff material such as diamond, sound travels at 12,000 m/s; which is around the maximum speed that sound will travel under normal conditions. Sound waves in solids are composed of compression waves (just as in gases and liquids), and a different type of sound wave called a shear wave, which occurs only in solids. History Basic concepts Compression and shear waves
File:FA-18 Hornet breaking sound barrier (7 July 1999) - filtered.jpg. Moon. Earth's natural satellite The Moon is in synchronous rotation with Earth, and thus always shows the same side to Earth, the near side. The near side is marked by dark volcanic maria that fill the spaces between the bright ancient crustal highlands and the prominent impact craters. After the Sun, the Moon is the second-brightest regularly visible celestial object in Earth's sky. Its surface is actually dark, although compared to the night sky it appears very bright, with a reflectance just slightly higher than that of worn asphalt.
Its gravitational influence produces the ocean tides, body tides, and the slight lengthening of the day. The Moon was first reached in September 1959 by the Soviet Union's Luna 2, an unmanned spacecraft, followed by the first successful soft landing by Luna 9 in 1966. Name and etymology Formation The Moon formed 4.51 billion years ago,[f] some 60 million years after the origin of the Solar System. The evolution of the Moon and a tour of the Moon Internal structure. Untitled. Star. For at least a portion of its life, a star shines due to thermonuclear fusion of hydrogen into helium in its core, releasing energy that traverses the star's interior and then radiates into outer space.
Once the hydrogen in the core of a star is nearly exhausted, almost all naturally occurring elements heavier than helium are created by stellar nucleosynthesis during the star's lifetime and, for some stars, by supernova nucleosynthesis when it explodes. Near the end of its life, a star can also contain degenerate matter. Astronomers can determine the mass, age, metallicity (chemical composition), and many other properties of a star by observing its motion through space, luminosity, and spectrum respectively. The total mass of a star is the principal determinant of its evolution and eventual fate. Other characteristics of a star, including diameter and temperature, change over its life, while the star's environment affects its rotation and movement.
Observation history Designations Age. File:The Sun by the Atmospheric Imaging Assembly of NASA's Solar Dynamics Observatory - 20100819.jpg. Mars. Fourth planet from the Sun in the Solar System Mars can easily be seen from Earth with the naked eye, as can its reddish coloring. Its apparent magnitude reaches −2.94, which is surpassed only by Venus, the Moon and the Sun. Optical ground-based telescopes are typically limited to resolving features about 300 kilometres (190 mi) across when Earth and Mars are closest because of Earth's atmosphere. Names In English, the planet is named for the Roman god of war, an association made because of its red color, which suggests blood. The adjectival form of Latin Mars is Martius, which provides the English words Martian, used as an adjective or for a putative inhabitant of Mars, and Martial, used as an adjective corresponding to Terrestrial for Earth. In Greek, the planet is known as Ἄρης Arēs, with the inflectional stem Ἄρε- Are-. From this come technical terms such as areology, as well as the adjective Arean and the star name Antares.
Physical characteristics Soil. 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 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 Later studies Name See also 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 In the case of radial motion: Transverse orbital speed 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 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 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 ) 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. 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. 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. Spiral galaxy containing our Solar System The Milky Way is a barred spiral galaxy with an estimated visible diameter of 150-200,000 light-years, an increase from traditional estimates of 100,000 light-years. Recent simulations suggest that a dark matter disk, also containing some visible stars, may extend up to a diameter of almost 2 million light-years. 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. Appearance Size and mass The structure of the Milky Way is thought to be similar to this galaxy (UGC 12158 imaged by Hubble) A schematic profile of the Milky Way.Abbreviations: GNP/GSP: Galactic North and South Poles Estimates of the mass of the Milky Way vary, depending upon the method and data used.
Contents The disk of stars in the Milky Way does not have a sharp edge beyond which there are no stars. Untitled. Solar wind. History 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. 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 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.