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North polar sequence
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1 July 2002: The Solar and Heliospheric Observatory (SOHO) satellite reveals a massive solar eruption more than 30 times the Earth's diameter. The eruption formed when a loop of a magnetic field over the surface of the Sun trapped hot gas.
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Nicolaus Copernicus. Nicolas Copernicus (1473-1543) Polish astronomer. In 1543 he published, forward proof of a Heliocentric (sun centered) universe. Coloured stipple engraving published London 1802. De revolutionibus orbium coelestium libri vi.
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North polar sequence

astronomy
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North polar sequence, group of 96 stars near the north celestial pole, used from about 1900 to 1950 as standards of magnitude and colour by which other stars are measured. First proposed by the American astronomer Edward Charles Pickering, the system has been largely superseded by the UBV system (q.v.).