“Moon * Mercury * Venus * Sun * Mars * Jupiter * Saturn
The ordering of the seven heavens is one of the mysteries of each culture, especially since it appears to be linked to everything. The Chaldeans created a very influential list, ordering the moon, Mercury, Venus, the sun, Mars, Jupiter, Saturn. This seems to reflect a very exact ascending order, based on the observed length of time that they circled the earth. The moon, as we know from our months, is 29.5 days, Mercury 88, Venus 224.7, the sun (the length of our year) is 365.25, Mars 687.1, while Jupiter is 12 years and Saturn 29.5.
This remains virtually the pattern we follow today, apart from the reordering of the sun-day as the first not the fourth. This ordering seems to have been achieved in the Hellenistic East, where we know that the Astrologers of Alexandria had created a hierarchy of sun, moon, Mars, Mercury, Jupiter, Venus, Saturn, which ascribed an order of dominant deities to each of the progressive hours of the daylight.”
Excerpted from: Rogerson, Barnaby. Rogerson’s Book of Numbers: The Culture of Numbers–from 1,001 Nights to the Seven Wonders of the World. New York: Picador, 2013.