How can prayer times be determined (especially the sun's decline) by knowing the hours, and what is the duration in hours between the Adhan and prayers in summer and winter?

We have previously explained the prayer times and how to determine the time of Zawwal (zenith) and midnight. These methods are easy for everyone to use, but the existence of calendars, mosques, and the adhan (call to prayer) makes it easier for Muslims to know the times. The duration between the appearance of true dawn and sunrise is approximately an hour and a half. The calendar is a means of knowing prayer times. It is obligatory to observe prayers at their prescribed times, as Allah the Almighty said: (And those who are constant in their prayers) [Al-Ma'arij/34], and He also said: (Guard strictly your prayers, especially the middle prayer; and stand before Allah with devotion) [Al-Baqarah/238]. The middle prayer is the Asr prayer. Despite the importance of calendars, they are a human endeavor that may contain errors, especially in determining the time of Fajr in some of them.