Cairo, 26th of Ramadan, 1443
Whether calculations or solely sightings determine valid prayer times is a question that falls within the jurisdiction of Islamic scholars and cannot be answered here. What we can answer are some questions about the advantages and disadvantages of the two opinions. Let's start with determining prayer times solely based on sightings. At first, it sounds very simple, as one only needs to find a place where the horizon can be observed. From this location, for example, Fajr would be observed and information about the current prayer time would be given. This would have to be done for every village and city in which Muslims reside. However, since this method is subject to strong influence from light pollution, the prayer times for each location would differ significantly. Thus, the village next to a brightly lit industrial plant would pray approximately 30 minutes later than the village 3 km away, which does not have as much artificial light on the horizon. Also, the prayer time would temporarily or slightly occur earlier if the power goes out. Thus, humans would be able to manipulate prayer times with their artificial light. Those who follow this opinion would have to agree to it as well. Cases where prayer calendars have been created through sightings are not known in Germany to this day. Proper creation of such a calendar would require long-term observations that document the times weekly and possibly several times a week.
The other opinion is that we calculate prayer times using values determined by observations. Muslims have been able to calculate prayer times based on the angle of the sun for about a thousand years. Ibn Shatir, the head of Mawaqit at the Umayyad Mosque in Damascus in 777 AH, said, "As for the time of the morning prayer, it is at daybreak, and if one knows this, one must place the nadir on the eighteenth arc in the direction of Maghrib." Western sources such as the New American Practical Navigator of 1802 also report on the angle of twilight: "With the preceding method, you can determine the beginning or end of twilight by calculating the hour when the sun's zenith distance is 108 degrees (or when the sun is 18 degrees below the horizon); for observation has shown that twilight begins or ends when the sun is at this distance from the zenith." This was long before science categorized the phases of twilight. The statements of Islamic astronomers and scholars from history as well as science are numerous and can be researched by anyone. The fact that Muslims are no longer in agreement today about which is the correct angle is due to several reasons. Firstly, most countries are too bright today to still recognize the initially very weak twilight, which includes the problem that sightings are made by people and in places that are not qualified for it. Secondly, based on interpretations of some astronomical texts, statements are made without ever having actually made a sighting. And there are also people who say that we should only follow the sighting in terms of the angle, without considering artificial light. They face the same problems as mentioned in the previous paragraph. Therefore, there cannot be a single degree value that applies to all locations, and one would have to determine a different degree value through observation for each village and city, which ultimately aligns with the other opinion. According to this opinion, one cannot say that the angle of Fajr is such and such, but only that in our location, the angle is such and such. If we believe that we should take artificial light into account and use the first visible light when no other electrical light is present as the basis for the beginning of dawn, then we must return to the values of the ancient astronomers and scientists. Because no one ever said that the first light of dawn appears at an angle lower than 18 degrees. Anyone who claims otherwise must adhere to the other opinion and may not represent any degree values in certain circumstances. Therefore, it can be said that the correct degree value for Fajr is 18, and Fajr can be observed at this degree value in areas without electrical light. Thus, Fajr can be calculated for any location in the world using this angle, which is the opinion of most scholars and astronomers in Islamic history.