corona

Corona, city, United States

Corona (kərō`nə), city (1990 pop. 76,095), Riverside co., S Calif.; inc. 1896. The city developed as a primary citrus fruit producer and shipping center. There is also light manufacturing. The name Corona ("circle") was derived from the 3 mi (5 km) circular drive around the city that was once used for car racing. State prisons for men and women are nearby. Cleveland National Forest and hot springs lie in the vicinity.

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corona, in astronomy

corona, luminous envelope surrounding the sun, outside the chromosphere. Its density is less than one billionth that of the earth's atmosphere. The corona is visible only at the time of totality during a total eclipse of the sun. It then appears as a halo of light with an irregular outer edge, often with streamers radiating from the sun's surface and contrasting with the dark lunar disk that it borders. It is divided into the inner corona, a ring of pale-yellow light against which crimson prominences are outlined, and the outer corona, a pearly white halo that extends far out into space. The corona consists of ionized gas at a temperature of 1 million°C;. By means of the coronagraph, the innermost part of the corona can be studied and photographed in full daylight. Although the visible corona extends a few solar radii above the sun, because of its high temperature it produces a continual flow of electrically charged particles called the solar wind that move outward through the solar system.

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corona

Total solar eclipse. The delicately structured glow of the solar corona—or solar …

(credit: Copyright AURA Inc./National Optical Astronomy Observatories/National Science Foundation)

Outermost region of the Sun's (or any star's) atmosphere, consisting of plasma. The Sun's corona has a temperature of about 3.6 million °F (2 million °C) and a very low density. Extending more than 8 million mi (13 million km) from the photosphere, it has no definite boundaries, continually varying in size and shape as it is affected by the Sun's magnetic field. The solar wind is formed by expansion of coronal gases. Only about half as bright as the full moon, the corona is overwhelmed by the brilliance of the solar surface and normally not visible to the unaided eye, but a total eclipse permits naked-eye observations.

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(1) See corona wire.

(2) (Corona) The code name for Windows Media Player 9, introduced in 2003. It improved the Windows Media Video codec and added the Windows Media Audio Professional codec for 5.1 surround sound at 24 bit, 96 kHz sampling. It also included Fast Stream, providing instant-on audio and video streaming for high-bandwidth connections.