On which periodic phenomenon are the following measures of time based: (i) day (ii) month (iii) year?
Day is based on the rotation of the Earth around its own axis, which takes approximately 24 hours and causes the cycle of day and night.
Month is based on the revolution of the Moon around the Earth and its cycle of phases, which takes approximately 29.5 days.
Year is based on the revolution of the Earth around the Sun, which takes approximately 365.25 days and corresponds to one complete cycle of seasons.
Explanation
(i) The chapter states: 'This natural cycle of the Sun due to the rotation of the Earth, is the foundation of the day, a unit to measure time.' (ii) The chapter states: 'The cycle of the phases of the Moon is the basis for a month, another unit to measure time.' (iii) The chapter states: 'The next larger unit to measure time is related to the natural cycle of seasons... the Earth revolves around the Sun and takes nearly 365 and a quarter days to complete one revolution around the Sun.'