Let us first recall from high school geography how the Sun's position on the horizon plane changes throughout the day. Determining the angles related to the Sun's elevation above the horizon helps us understand local time. On a diagram of the horizon plane drawn on paper, the right side always represents the east — the direction of sunrise — while the left side represents the west — the direction of sunset. From sunrise until noon, the Sun rises on the horizon plane; after noon, it begins to descend. The moment the Sun reaches its highest point on the horizon plane during the day is noon, which corresponds to the exact midpoint of the day. If the duration of daylight is known, the times of sunrise and sunset can be calculated by dividing the day symmetrically around noon. In problems involving the horizon plane, if the duration of daylight and the Sun's angles on the horizon are known, it is possible to calculate local time.
Different calendars are used around the world to calculate prayer times. However, it should not be forgotten that calendars yielding accurate results must be based on scientific data. The Süleymaniye Foundation Calendar was established in accordance with the Quran as a result of extensive research and calculations carried out by Abdülaziz Bayındır. This calendar differs from others in determining prayer times and is calculated in accordance with observation and the expressions found in the Holy Quran. In Turkey, three different calendars are in use: the Diyanet, Fazilet, and Süleymaniye Foundation calendars. The Süleymaniye Foundation Calendar is the most accurate calendar, proven correct through scientific calculations. The other calendars are contrary to both astronomy and the Quran. Various calendars also exist worldwide:
- Diyanet Calendar (Turkey): Despite being the official calendar, it contradicts astronomical data and the Quran.
- Fazilet Calendar: Used by many mosques and Muslim communities in Turkey, but contrary to both astronomy and the Quran.
- Umm al-Qura Calendar (Saudi Arabia): The calendar used in Saudi Arabia.
- Muslim World League (MWL): An internationally recognized method.
- ISNA: A method widely used in North America.
- Other Countries: Local calendars adapted according to geographic and denominational characteristics — for example, different calendars are used in Iran, Pakistan, Indonesia, and Singapore.
The Süleymaniye Foundation Calendar is accepted as the calendar that determines the most accurate prayer times.
Prayer is one of the fundamental acts of worship in Islam — a regular practice aimed at fostering the spiritual development of a person at every moment of daily life. Determining prayer times correctly must be done with an understanding that aligns with both religious beliefs and scientific observations. The Quran contains various indicators for determining prayer times, explaining them based on natural phenomena. Expressions in the Quran link prayer times to events in nature. For example, the beginning of the morning prayer (Fajr) is defined as fajr al-sadiq (the true dawn — the brightening of the horizon), while the beginning of the evening prayer is associated with sunset. These times have also been arranged in accordance with people's biological clocks and established to provide a balance in daily life.
The time of the morning prayer begins when the black and white lights in the sky become distinguishable from one another. Fajr al-sadiq refers to the moment when light begins to spread across the eastern horizon. The Quran expresses this as follows:
> "And establish prayer at the two ends of the day and at the approach of the night. Indeed, good deeds do away with misdeeds. That is a reminder for those who remember." (Hud, 11:114)
This verse defines the beginning of the morning prayer as the brightening of the dawn and indicates that it continues until sunrise.
The times of the noon and afternoon prayers are determined according to the length of shadows and the position of the Sun. The noon prayer begins from the moment the Sun starts to shift westward from its highest point and ends when the shadow of an object exceeds its own length. This time can be calculated, as taught in geography lessons, up to half the length of the day. The afternoon prayer begins when the shadow reaches twice the length of the object and ends shortly before sunset.
The time of the evening prayer begins at sunset, and we wait for the beginning of the night — that is, the onset of darkness. When the evening time ends, the red and white lights in the sky have blended into the darkness of night. The night prayer begins when the red and white lights in the sky have completely disappeared and darkness has taken hold. The time of the night prayer is the moment when even the faintest stars have become visible and complete darkness has enveloped the sky.
Prayer times must be determined based on astronomical calculations. The General Directorate of Meteorology determines sunrise and sunset times using astronomical data, and these data yield accurate results. While Allah provides clues in the Quran for determining prayer times, He proposes an order suited to the daily rhythms of human beings. The movements of the Sun are part of nature's cycles, and prayer times should be determined in harmony with this cycle.
Accurate determination of prayer times requires both scientific data and an approach grounded in the Quran. Meteorological and astronomical calculations provide a correct path for determining prayer times. The fact that the Süleymaniye Foundation's calendar yields accurate results based on astronomical data — while other calendars show discrepancies — demonstrates the correctness of the Süleymaniye Foundation's approach. Paying attention to natural phenomena under the guidance of the Quran in determining prayer times is a guarantee of correct religious practice.
Süleymaniye Foundation Prayer Time Calculations
The methods used by the Süleymaniye Foundation to determine sunrise, sunset, and prayer times are precisely regulated based on astronomical calculations. According to the calculations used by the Foundation, critical times such as imsak (pre-dawn meal cutoff), fajr al-sadiq (true dawn), and fajr al-kadhib (false dawn) are anchored to specific angles of the Sun relative to the horizon.
- Imsak Time (Fajr al-Sadiq)
Imsak is the time for performing the morning prayer. The Süleymaniye Foundation uses the moment when the Sun is at −9 degrees below the horizon as the reference for imsak. This calculation is consistent with astronomical observations and is carried out using a specific angle with correct criteria. Known as Fajr al-Sadiq (the true dawn), this time is the moment when the first lights begin to become distinct in the sky; it marks both the entry of the morning prayer time and the point at which those who are fasting must cease eating and drinking.
Seher Time (Fajr al-Kadhib)
Fajr al-Kadhib (the false dawn) refers to the false early glimmers observed in the early hours of the day that are not valid for fasting purposes. These glimmers are observed when the Sun is at −18 degrees below the horizon. Fajr al-Kadhib marks a period before the true Fajr al-Sadiq; the morning prayer cannot be performed at this time, and those who are fasting may still eat and drink.
Solar Altitude and Azimuth
In the Süleymaniye Foundation's calculations, sunrise and sunset times are determined using astronomical data such as the Sun's altitude and azimuth (direction). These data are calculated in accordance with latitude, longitude, and the local time zone. Sunrise occurs in the eastern direction at the exact moment the Sun first makes contact with the horizon. Similarly, sunset is the moment the Sun leaves the horizon in the western direction.
Astronomical Calculations and Formulas
In performing these calculations, the Süleymaniye Foundation primarily uses astronomical formulas that determine the Sun's position on Earth. These calculations are generally based on factors such as solar declination and hour angle. These formulas are adjusted according to the observed latitude and longitude when determining sunrise and sunset times.
- Solar Declination (δ): Determines the Sun's vertical position in the sky and changes throughout the year. This value varies seasonally.
- Hour Angle (H): Determines the Sun's position in the local time zone and indicates when the Sun will reach a specific point.
Astronomical software or specialized calculation tools can be used for these calculations. The Süleymaniye Foundation also makes use of various astronomical databases and software to carry out such calculations accurately.
Creating and Using the Calendar
Each year, the Süleymaniye Foundation prepares calendars containing daily prayer times and imsak times, taking into account local geographic location and latitude information. In these calendars:
- The imsak (Fajr al-Sadiq) time is calculated based on the Sun's position at −9 degrees below the horizon.
- Sunrise and sunset times are likewise determined through astronomical calculations.
- Each prayer time is calculated based on the Sun's position and reflected in the calendar.
Creating a Calendar Based on Süleymaniye Foundation Calculations Using Python
Using the Python programming language and astronomical libraries such as ephem, it is possible to calculate imsak, fajr al-kadhib, and sunrise and sunset times in accordance with the calculation methods used by the Süleymaniye Foundation. Below is a simple Python code example that performs these calculations for the province of Aydın:
Install the required libraries:
pip install ephem pytz
python
import ephem
from datetime import datetime
import pytz
def sun_times(latitude, longitude, date):
observer = ephem.Observer()
observer.lat = str(latitude)
observer.lon = str(longitude)
observer.date = date
sunrise = observer.next_rising(ephem.Sun()).datetime()
sunset = observer.next_setting(ephem.Sun()).datetime()
IMPORTANT: ephem returns UTC but as naive datetime
utc = pytz.utc
sunrise = utc.localize(sunrise).astimezone(pytz.timezone("Europe/Istanbul"))
sunset = utc.localize(sunset).astimezone(pytz.timezone("Europe/Istanbul"))
return (
sunrise.strftime('%Y-%m-%d %H:%M:%S'),
sunset.strftime('%Y-%m-%d %H:%M:%S')
)
latitude = 37.8667
longitude = 27.8386
date = '2026-03-24'
sunrise, sunset = sun_times(latitude, longitude, date)
print(f"For Aydın on {date}:\nSunrise: {sunrise}\nSunset: {sunset}")
This example calculates sunrise and sunset times for Aydın using the ephem library. When the −9 degree calculation criterion is applied to correctly determine the imsak time, the times are calculated accurately. Building a more advanced system requires API or database integration. If you wish to perform automatic calculations for different locations, you should develop a system that determines the location based on the user's IP address or manual input.
According to the calculation method used by the Süleymaniye Foundation, −9 degrees below the horizon is used for the imsak time, and −18 degrees is accepted for the seher time (fajr al-kadhib). These calculations, based on astronomical data, determine prayer and fasting times in accordance with the Quran. These methods, calculated using correct criteria, not only facilitate daily life but also help ensure that Islamic acts of worship are performed at the correct times.
