Answer:
the sun and moon cycle takes up 24 hours, so that is why a whole day is considered 24 hours. there are 7 days in a week based on the earths rotation and position on its axis. there are 12 months in a year because of the lunar cycles, there are just a little bit over 12 in a year. we also have been following this stuff since the time of the ancient babylons and maybe even before.
