The Quran says about fasting:

كُتِبَ عَلَيْكُمُ الصِّيَامُ كَمَا كُتِبَ عَلَى الَّذِينَ مِنْ قَبْلِكُمْ (2:183) 'Believers, fasting has been prescribed for you, just as it was prescribed for those before you.''

This is very important. Fasting is a universal tradition. It has been continuing throughout history since the time of prophets. God has always commanded His servants to fast, and this is also part of Islam. Fasting is a universal tradition. Ramadan is the ninth month of the Hijri calendar. The new moon is sighted on the last day of Shaban. The sighting of the new moon begins the month of fasting. At morning twilight, the first sign of sunrise emerge on the horizon. That marks the beginning of fasting. And it ends with sunset. The duration of fasting is from morning twilight to sunset. The sun and the moon are involved in this.

Sighting of the new moon begins the fasting month. Sunrise and sunset determine the beginning and end of the fast in a day. We live on earth, but follow commands from the sky. This is a reminder telling us we are subjects of God. We have to follow God's orders. We live on the earth, which is about 150 million miles away from the sun. We decide the fasting duration based on the earth's movement around the sun. This signifies that humans are subject to God high above. We have to follow God's commands. We can say that the month of Ramadan is a refresher course. One month of the year is chosen to provide a refresher course. We have to spend the rest 11 months according to the training received in Ramadan.