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		<field id="8018" index="0" type="number">23032</field>

		<subject index="0" >Re: THIRD TARGET - GLOBULAR CLUSTER M3</subject>

		<tonames index="0" >S194 06E real time observing</tonames>

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A colour-magnitude diagram is a version of the well-known Hertzsprung-Russell diagram.  When we plot the intrinsic brightness (vertically) against the colour (horizontally) of stars we find the stars tend to fall only in certain patches.  There is a diagonal line of stars called the Main Sequence (great name?), and our Sun is one of these.  We also find a group of red giants, and a group of supergiant stars.  
Andy Norton on 15 May 2006 at 22:46 +0000 wrote:
construct a colour-magnitude diagram for you from these data