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Xi Boo is a long-period binary star system discovered by William Herschel in 1780, when the stars were 4" apart. In May 2003 the separation between this pair of stars is 6.5", making them an easy target in most telescopes. The primary star is a magnitude 4.5, G8 main sequence star, much like our sun. The fainter component is 7th a magnitude K4 star, also on the main sequence. This star is much cooler and redder than the yellow-white primary, making for a fine contrast in color. The two lie at a relatively nearby distance of 22 light years and take 151 years to complete one orbit. The average separation between the two is about 30 AU, or 30 times the distance between the earth and sun. If the primary star were placed at the sun, the secondary would orbit near Neptune. The pair have completed ~1.5 orbits since Herschel's discovery. Near maximum separation today, they will close in the coming decades until 2058, when they will be separated by a mere 2.4". 
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