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Message: <blockquote data-quote="Binastro" data-source="post: 3545764" data-attributes="member: 111403">A simplified calculation gives 18.4 degrees for the angle between Betelgeuse and Rigel.A map measure about 18.35 deg or 18.4 deg.But I haven't done an exact calculation.In daylight with rested eyes the image was sharper with old distance glasses.At night reading glasses were better and Orion stars were sharp.I think my eyes change focus night or day and if tired or not.P.S.Taking star positions for 2017.5, a simplified but more accurate calculation gives a maximum of 18.62 degrees.One can do this because the two stars straddle the celestial equator and are not far from it.However, The University of Texas at Arlington, Planetarium gives 18.56 degrees, which seems correct.The trouble with measuring maps is especially difficult as the pages fold at the equator, although digital maps are better.</blockquote>