Erablian t1_jabcrc5 wrote on February 28, 2023 at 5:00 AM Reply to comment by annomandaris in Eli5: How did people know how long a year was in olden times? by Slokkkk The synodic month averages 29.53 days, quite a bit different from your 28-day month. After 13 of those, your calendar would be 9.6 days out of sync with the actual phase of the moon. 13 synodic months is about 384 days, not 364. Permalink Parent 1
Erablian t1_jabcrc5 wrote
Reply to comment by annomandaris in Eli5: How did people know how long a year was in olden times? by Slokkkk
The synodic month averages 29.53 days, quite a bit different from your 28-day month. After 13 of those, your calendar would be 9.6 days out of sync with the actual phase of the moon.
13 synodic months is about 384 days, not 364.