In the earlier lessons, we learned that a day is the duration of one rotation of the Earth about its axis while a year is the duration of one revolution of the Earth around the Sun. Can you think of another way in which we measure the time?

We divide a year into months. Does a month have a relation to any astronomical phenomenon?

The phases of the Moon were used to measure the time in many ancient cultures. The word, ’month’ comes from the Moon cycle. In many of the old calendars (e.g., Chaitri Panchanga, Hijri calendar) a month is a period from one new Moon to the next.