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The biggest rocket built to date, weighing 2700 tons fully loaded. It was used to launch NASA's Moon mission and the Skylab space station.
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A fundamental law of energy exchange, one of whose formulations is "no process is possible whose only net effect is the flow of heat from a cold body to a hot one." A consequence of this is that in any system only part of the heat energy can be converted to other forms; the rest of the heat flows to lower temperature.
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a property of an ellipse, equal to half its greatest width, as measured along the line connecting its two foci. The semi-major axis of an orbital ellipse is one of the "orbital elements" characterizing it, and is directly related to the energy of the motion.
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A sudden transition at the front of fast flow of plasma or gas, when that flow moves too fast for the undisturbed gas to move out of its way. Also occurs when a steady fast flow hits a magnetic or solid obstacle.
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A general term for those processes and changes on the Sun that rise and fall with the sunspot cycle, e.g. flares.
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(or sunspot cycle)--an irregular cycle, averaging about 11 years in length, during which the number of sunspots (and of their associated outbursts) rises and then drops again. Like the sunspots, the cycle is probably magnetic in nature, and the polar magnetic field of the Sun also reverses each solar cycle.
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high energy particles occasionally emitted from active areas on the Sun, associated with solar flares and coronal mass ejections. The Earth's magnetic field keeps them out of regions close to Earth (except for the polar caps) but they can pose a hazard to space travelers far from Earth.
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A fast outflow of hot gas in all directions from the upper atmosphere of the Sun ("solar corona"), which is too hot to allow the Sun's gravity to hold on to its gas. Its composition matches that of the Sun's atmosphere (mostly hydrogen) and its typical velocity is 400 km/sec, covering the distance from Sun to Earth in 4-5 days. The solar wind confines the Earth's magnetic field inside a cavity known as the magnetosphere and supplies energy to phenomena in the magnetosphere such as polar aurora ("northern lights") and magnetic storms.
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Rockets which burn a solid mixture of fuel and oxidizer, and have no separation between combustion chamber and fuel reservoir. Gunpowder is such a mixture and was the earliest rocket fuel. They are somewhat less efficient than the best liquid fuel rockets, but are preferred for military use because they need no lengthy preparation and are easily stored in ready-to-fly condition. They are also used in auxiliary rockets that help heavily loaded liquid-fuel rockets (Space Shuttle, Delta) lift off and go through the first stage of their flight.
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A habitable orbiting structure with a rotating crew and regular resupply.
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A narrow range of spectral color, emitted (or absorbed) by a specific atom (or molecule).The energy of its photon corresponds to the difference between two energy levels of the atom, and such photons are emitted when the atom "falls" from the higher level to the lower one.
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In the original meaning, the spread of colors seen in the rainbow, covering all pure colors the eye can see. Spectrum of a substance, e.g. of an atomic element, is the collection of spectral lines emitted by it.
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("satellite") The first artificial Earth satellite, orbited by the Soviet Union on October 7, 1957, using Korolev's R-7 rocket.
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The placing of smaller rockets on top of larger ones, increasing the lifting ability of the combined set-up.
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(stellar=of a star) The different phases in the lifetime of a star, from its formation out of gas and dust, to the time after its nuclear fuel is exhausted. Based on observations of stars at various stages of their evolution, astronomers have developed a general theory of stellar evolution, by which the Sun is a typical "main sequance" star, in the middle of its evolutionary lifespan.
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The layer of the atmosphere above the troposphere. In the troposphere temperature decreases fairly rapidly with increasing altitude, in the stratosphere it changes only slowly--approximately constant at the lower edge (10-16 kilometers), rising moderately at 25-40 km due to heating by ultra-violet sunlight, which is absorbed there by ozone. The difference arises because in the troposphere, heat is carried away from the Earth mainly by up-and-down flows associated with convection, in the stratosphere heat is radiated outwards, with little flow motion.
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A device for telling time of day by the shadow which sunlight produces on the instrument. See gnomon.
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An intensely magnetic area on the Sun's visible face. For unclear reasons, it is slightly cooler than the surrounding photosphere (perhaps because the magnetic field somehow interferes with the outflow of solar heat in that region) and therefore appears a bit darker. Sunspots tend to be associated with violent solar outbursts of various kinds.
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(More accurately, type II supernova.) When a star burns up all its fuel, it collapses and the released gravitational energy blows off its top layers, creating a supernova explosion. What remains of the star depends on its mass. Low-mass stars crush their atoms and become white dwarfs, about as big as Earth. High mass stars collapse into black holes whose gravity prevents any light from escaping. Stars with masses between those extremes collapse into neutron stars, consisting of extreme dense nuclear matter held together by gravity and nuclear force, with a radius of the order of 10 km.
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the angle by which the wing of an airplane is swept back, measured from the direction perpendicular to the fuselage.
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The circular orbit above the equator at a distance of 6.6 Earth radii, in which a spacecraft has an orbital period of 24 hours. Such satellites stay above the same spot on Earth and are therefore ideally suited for transmitting communications and broadcasts.
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