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colour-magnitude diagram
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A Hertzsprung-Russell diagram plots absolute visual magnitude against color index for Population II stars in a globular cluster, highlighting regions for horizontal branch, red giants, lower main sequence, blue stragglers, and the RR Lyrae gap. Spectral classes B through M are marked along the top axis.
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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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Hertzsprung-Russell diagram
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colour-magnitude diagram

astronomy
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colour-magnitude diagram, in astronomy, graph showing the relation between the absolute magnitudes (brightnesses) of stars and their colours, which are closely related to their temperatures and spectral types. It is similar to the Hertzsprung-Russell diagram except that the latter plots spectral types instead of colours.

This article was most recently revised and updated by Erik Gregersen.