Quran verse 10:5 “It was He that made the sun a brightness and the moon a light, and determined it in positions so that you might know the number of years and the reckoning. Allah did not create them except in truth, and distinguishes the verses to a nation who know.”
When you are in a boat in the middle of the ocean, you only see water in all directions. And the captain can determine his position in the ocean by knowing the latitude and longitude. By calculating the angle of the polar star he can know the latitude. By calculating the speed of the boat and the time, he can know the longitude also. Thus it became clear that the computation of time is essential for the boat crew to survive
Quran verse 36:38 “The sun runs to its fixed restingplace; that is the decree of the Almighty, the Knower”.
A restingplace “mustaker” is a specific place in a space that has its own character and can be used for residence and motion in it according to the rules of these characteristics. As God say “and you will have upon the earth a place of settlement and provision for a time.”Baqarah (36)” That is, life is under the laws of the earth, and this is God’s estimation for that.
Nobody can locate the sun in space. But it is necessary to know the location of the earth around the sun, because this is a life necessity to know the seasons of the year, as is evident from the verse: “Allah did not create them except in truth” and this is the role of the moon for that. Therefore, it is necessary to name the months due to their properties, distinction and knowledge to determine the seasons.
If the calculation method does not fulfill this condition, then we will be like the captain of the boat if he does not know where he is in the middle of the ocean.