Flux of particles, chiefly protons, electrons, and helium nuclei, accelerated by the hot solar corona's high temperatures to speeds high enough to allow them to escape the Sun. Solar flares increase its intensity. The solar wind deflects planets' magnetospheres and the ion tails of comets away from the Sun. The uninterrupted portion of the solar wind continues to travel to a distance of about 110–170 astronomical units, where it cools and eventually diffuses into interstellar space. Seealso heliopause.
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The Sun, its eight major planets, the dwarf planets and small bodies, and interplanetary dust and gas under the Sun's gravitational control. Another component of the solar system is the solar wind. The Sun contains more than 99percnt of the mass of the solar system; most of the rest is distributed among the planets, with Jupiter containing about 70percnt. According to the prevailing theory, the solar system originated from the solar nebula. Seealso asteroid; Centaur object; Ceres; comet; Earth; Eris; Jupiter; Kuiper belt; Mars; Mercury; meteorite; Neptune; Oort cloud; Pluto; Saturn; Uranus; Venus.
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Arched stream of hot gas projecting from the Sun's surface into the chromosphere or corona. Prominences can be hundreds of thousands of miles long and can be seen with the unaided eye during a total eclipse. They appear to lie along and are supported by loops in the Sun's magnetic field, where they may remain for days to months.
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Radiation from the Sun that can produce heat, generate electricity, or cause chemical reactions. Solar collectors collect solar radiation and transfer it as heat to a carrier fluid. It can then be used for heating. Solar cells convert solar radiation directly into electricity by means of the photovoltaic effect. Solar energy is inexhaustible and nonpolluting, but converting solar radiation to electricity is not yet commercially competitive, because of the high cost of producing large-scale solar cell arrays and the inherent inefficiency in converting light to electricity.
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Gaseous cloud from which, in the nebular hypothesis of the origin of the solar system, the Sun and planets formed by condensation. In 1755 Immanuel Kant suggested that a nebula gradually pulled together by its own gravity developed into the Sun and planets. Pierre-Simon, marquis de Laplace, in 1796 proposed a similar model, in which a rotating and contracting cloud of gas—the young Sun—shed concentric rings of matter that condensed into the planets. But James Clerk Maxwell showed that, if all the matter in the known planets had once been distributed this way, shearing forces would have prevented such condensation. Another objection was that the Sun has less angular momentum than the theory seems to require. In the early 20th century most astronomers preferred the collision theory: that the planets formed as a result of a close approach to the Sun by another star. Eventually, however, stronger objections were mounted to the collision theory than to the nebular hypothesis, and a modified version of the latter—in which a rotating disk of matter gave rise to the planets through successively larger agglomerations, from dust grains through planetesimals and protoplanets—became the prevailing theory of the solar system's origin.
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Use of solar radiation to heat water or air in buildings. There are two types: passive and active. Passive heating relies on architectural design; the building's siting, orientation, layout, materials, and construction are utilized to maximize the heating effect of sunlight falling on it. A well-insulated building with a large south-facing window, for instance, can trap heat on sunny days and reduce reliance on gas, oil, or electricity. Brick, stone, or tile capacity walls are often incorporated to absorb the sun's energy and radiate it into the interior, usually after a time lag of several hours. In active solar heating, mechanical means are used to collect, store, and distribute solar energy. In liquid-based systems, a blackened metal plate on the exterior absorbs sunlight and traps heat, which is transferred to a carrier fluid. Alternatively, fluid may be pumped through a glass tube or volume of space onto which sunlight has been focused by mirrors. After picking up heat from the collector, the warm fluid is pumped to an insulated storage tank. The system can supply a home with hot water from the tank or provide space heating with the warmed water flowing through tubes in floors and ceilings.
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Sudden intense brightening of a small part of the Sun's surface, often near a sunspot group. Flares develop in a few minutes and may last several hours, releasing intense X rays and streams of energetic particles. They appear to be connected with changes in the Sun's magnetic fields during the solar cycle. The ejected particles take a day or two to reach the vicinity of Earth, where they can disrupt radio communications and cause auroras, and may pose a radiation hazard to astronauts.
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Period in which several important kinds of solar activity repeat, discovered in 1843 by Samuel Heinrich Schwabe (1789–1875). Lasting about 22 years on average, it includes two 11-year cycles of sunspots, whose magnetic polarities alternate between the Sun's northern and southern hemispheres, and two peaks and two declines in the phenomena (e.g., solar prominences, auroras) that vary in the same period. Attempts have been made to connect the solar cycle to various other phenomena, including possible slight variations in the diameter of the Sun, sequences of annual growth rings in trees, and even the stock market's rise and fall.
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Total solar eclipse. The delicately structured glow of the solar corona—or solar elipsis
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When sunlight strikes a solar cell, an electron is freed by the photoelectric effect. The two elipsis
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A solar powered pump thus consist of 2 parts :