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Variable Star
A variable star is a star whose brightness as seen from Earth (its apparent magnitude) changes with time. This variation may be caused by a change in emitted light or by something partly blocking the light, so variable stars are classified as either: * Intrinsic variables, whose luminosity actually changes; for example, because the star periodically swells and shrinks. * Extrinsic variables, whose apparent changes in brightness are due to changes in the amount of their light that can reach Earth; for example, because the star has an orbiting companion that sometimes eclipses it. Many, possibly most, stars have at least some variation in luminosity: the energy output of the Sun, for example, varies by about 0.1% over an 11-year solar cycle. Discovery An ancient Egyptian calendar of lucky and unlucky days composed some 3,200 years ago may be the oldest preserved historical document of the discovery of a variable star, the eclipsing binary Algol. Of the modern astronomers, th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
VISTA Views The Trifid Nebula And Reveals Hidden Variable Stars
Vista usually refers to a distant view. Vista may also refer to: Software *Windows Vista, the line of Microsoft Windows client operating systems released in 2006 and 2007 *VistA, (Veterans Health Information Systems and Technology Architecture) a medical records system of the United States Department of Veterans Affairs and others worldwide *VISTA (comparative genomics), software tools for genome analysis and genomic sequence comparisons *VistaPro, and Vista, 3D landscape generation software for the Amiga and PC *VIsualizing STructures And Sequences, bioinformatics software Organizations and institutions *Vista Entertainment Solutions, a New Zealand software company specializing in solutions for the cinema industry *AmeriCorps VISTA, a national service program to fight poverty through local government agencies and non-profit organizations *Ventura Intercity Service Transit Authority, a public transportation agency in Ventura County, California, US *Vista Community College, now Be ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
