Calendars Flashcards
Astronomical cycles
Days
Months
Years
Days
Earth’s rotation on its axis
Months
Revolution of the moon around the earth
Years
Revolution of the earth around the sun
Types of years
Tropical
Lunar
Lunisolar
Tropical year
Interval Between Vernal Equinoxes: 365.242
Solar
Twelve Synodic Lunar Phases: 365.367
Lunisolar
Mechanical Division of Sequences: 365
Calendar systems
Solar
Lunar
Lunisolar
Solar system
Synchrony with the Tropical year
Days intercalated to form leap years
Examples: Gregorian and Julian
Lunar system
Follows lunar phases without seasons
Months shift per annum
Examples: Islamic and Zoroastrian
Lunisolar system
Months based on lunar phases
Interlaced to synchronize seasonally
Examples: Hebrew and Chinese
Why do we need to know about calendars etc.?
The way we view time tells us much about our worldview.
How we measure our time helps us to know what to do with our time.
we must be intentional about the way we view and organize our time.
“Every day that passes should be lived in light of the past, in light of the future, and in light of eternity.”
Thomas Chalmers
Julius devised intercalary synchrony
45 bc
