 ©L. Ondra
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When viewed by eye, Mizar appears as a
single star which lies 11 arcminutes from a bright star known as Alcor. These
stars are not physically associated - they are merely an "optical
double".
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When viewed in a telescope, Mizar is a visual binary, with its two
components, Mizar A and B separated by about 15 arcseconds. The
pair orbit each other approximately twice per year.
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©J. Benson et al., NPOI
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Amazingly, Mizar A is itself a visual binary,
with a separation of approximately 10 milli-arcseconds and an
orbital period of 20.5 days.
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