The days are named after the planets
Sunday belongs to the Sun, Monday to the Moon, Tuesday to Mars, Wednesday to Mercury, Thursday to Jupiter, Friday to Venus and Saturday to Saturn — in Sanskrit as in English. That accounts for the first day in every row: Mulank 9 is Mars, so Tuesday leads. The extra days come from planets the tradition treats as friendly to yours. Those secondary days are the part that varies between books; this page uses the common Cheiro-derived list rather than pretending there is only one.
