- published: 06 Jun 2015
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A planet (from Ancient Greek αστήρ πλανήτης (astēr planētēs), meaning "wandering star") is a celestial body orbiting a star or stellar remnant that is massive enough to be rounded by its own gravity, is not massive enough to cause thermonuclear fusion, and has cleared its neighbouring region of planetesimals. The term planet is ancient, with ties to history, science, mythology, and religion. The planets were originally seen by many early cultures as divine, or as emissaries of deities. As scientific knowledge advanced, human perception of the planets changed, incorporating a number of disparate objects. In 2006, the International Astronomical Union (IAU) officially adopted a resolution defining planets within the Solar System. This definition has been both praised and criticized, and remains disputed by some scientists since it excludes many objects of planetary mass based on where or what they orbit.
The planets were thought by Ptolemy to orbit the Earth in deferent and epicycle motions. Although the idea that the planets orbited the Sun had been suggested many times, it was not until the 17th century that this view was supported by evidence from the first telescopic astronomical observations, performed by Galileo Galilei. By careful analysis of the observation data, Johannes Kepler found the planets' orbits to be not circular, but elliptical. As observational tools improved, astronomers saw that, like Earth, the planets rotated around tilted axes, and some shared such features as ice caps and seasons. Since the dawn of the Space Age, close observation by probes has found that Earth and the other planets share characteristics such as volcanism, hurricanes, tectonics, and even hydrology.
Gustav Theodore Holst (born Gustavus Theodore von Holst, 21 September 1874 – 25 May 1934) was an English composer. He is most famous for his orchestral suite The Planets.
His early works show the influence of Grieg, Wagner,Richard Strauss and fellow student Ralph Vaughan Williams, and later, through Vaughan Williams, the music of Ravel. The combined influence of Ravel, Hindu spiritualism and English folk tunes enabled Holst to free himself of the influence of Wagner and Strauss and to forge his own style. Holst's music is well known for unconventional use of metre and haunting melodies.
Holst composed almost 200 works, including operas, ballets, choral hymns and songs. An enthusiastic educator, Holst became music master at St Paul's Girls' School in 1905 and director of music at Morley College in 1907, continuing in both posts until retirement. He also taught singing at Wycombe Abbey School from 1912 until 1917.
He was the brother of Hollywood actor Ernest Cossart and father of the composer and conductor Imogen Holst, who wrote a biography of him in 1938.