How do the scriptures differentiate between a Deva year and a normal human year? Which beings and Lokas are under the effect of Deva year?
Q. How do the scriptures differentiate between a Deva year and a normal human year?
We know the year calculation is as follows:
15 days & nights = 1 fortnight
2 fortnights = 1 month
2 months = 1 season
6 months = 1 ayan (complete movement of sun from north to south)
2 ayans = 1 year
Now the comparison between year of human beings and Devas is:
Answer: 1 year for human being = 1 day & night for Devas
11th Chapter of 3rd Canto of Srimad Bhagavatam comprehensively describe the calculation of time. Quoting from Chapter 11: Calculation of Time, from the Atom
Text 10: It is calculated that there are four praharas, which are also called yāmas, in the day and four in the night of the human being. Similarly, fifteen days and nights are a fortnight, and there are two fortnights, white and black, in a month.
Text 11: The aggregate of two fortnights is one month, and that period is one complete day and night for the Pitā planets. Two of such months comprise one season, and six months comprise one complete movement of the sun from south to north.
Text 12: Two solar movements make one day and night of the demigods, and that combination of day and night is one complete calendar year for the human being. The human being has a duration of life of one hundred years.