Date Numerology
There are various different ways of adding up the numbers in a date to work out its date numerology. The number of the day in the year and the number of days to the end of the year is also relevant.
The Brown lunation number is the number of lunations (cycles of the moon from new moon to new moon) beginning with the new moon on 1923-01-17 as lunation 1. The Janus lunation number is the number of lunations from the new moon of 2000-01-06 as lunation 0.