According to the book 'Popular Astronomy' by Simon Newcomb, published in 1878, page 46, astrologers of yore drew a circle and inesribed a 7-pointed star. They ordered the seven known celestial bodies in order of increasing distance from the Earth ' Moon, Mercury, Venus, Sun, Mars, Jupiter and Saturn in a counterclockwise pattern on the circumference at each point of the star. Then in a natural pattern of strokes, drew the segments of the star starting with the Moon.
Monday..... First point. Tuesday.... Mars Wednesday.. Mercury Thursday.. Jupiter Friday.... Venus Saturday.. Saturn Sunday.... SunIn Spanish, we even hear the names of the planets more clearly: Lunes, martes, miercoles, queves, viernes, sabado domingo...if I recall my spellings correctly!