I was working on the Prayer Times when I stumbled upon the notion of the position of the Sun in Wikipedia. I was converting the Javascript codes into C and made a major restructuring of the codes so that I know what was the main contributor. It was the position of the Sun. All Muslim prayer times are related to solar events such as sunrise, noon and sunset.
The details of the calculation of the position of the Sun are involved. The true relationship between the Earth and the Sun is never constant. The method that is given by Wikipedia is just an approximation which is good enough for few decades to come. Hopefully by that time we already have a better approximation.
The events of sunrise to sunset are due to the Earth rotation on its polar axis. Never expect the Sun's circling the Earth to be in the perfect 24 hour rotation. The noon is never at the same time every day. This is due to the motion of the Earth orbiting the Sun. The orbit is not a perfect circle and the speed of the Earth orbiting the Sun is not constant. Through out a year there are days that are slightly more than 24 hours and there are days that are slightly less than 24 hours. There are more. There are days when both the sunrise and sunset are early. And there are days when both the sunrise and sunset are late. These lead to the equation of time.
The Sun does not always exactly rise from the east and set to the west. Through out a year its path declines northward and then southward, and then back again. This is due to the tilting of the Earth's polar axis. Hence, from an observer point of view at noon facing south or north the Sun angle is not the same through out the year. This is known as the declination of the Sun. It is contributing to the longer or shorter days and nights through out a year. Hence, it determines the actual times of sunrise and sunset which are gradually shifting back and forth through out a year.
The Sun appears to be oscillating on all axes of the Earth.
To know the position of the Sun anywhere on the Earth at any given time we need to calculate the declination of the Sun and the equation of time. See the details in Wikipedia. The calculation is based on Julian day.
If the Earth rotation is in the perfect 24 hours and the Sun always rises from the East and sets to the West then given any angle of the Sun on the solar disc we can easily calculate the time. Hence, the calculation of the prayer times will be easy and we don't have to do it every day because it will be the same every day. However, the reality is different. We have to factor the declination of the Sun and the equation of time in our calculation and we have to calculate the prayer times every day.
Apart from prayer times, the codes to calculate the position of the Sun can be used for other purposes such as a device to track the Sun, or a controller that works based on the exact day and night times. I have tested the C codes to run perfectly in ESP8266.
The details of the calculation of the position of the Sun are involved. The true relationship between the Earth and the Sun is never constant. The method that is given by Wikipedia is just an approximation which is good enough for few decades to come. Hopefully by that time we already have a better approximation.
The events of sunrise to sunset are due to the Earth rotation on its polar axis. Never expect the Sun's circling the Earth to be in the perfect 24 hour rotation. The noon is never at the same time every day. This is due to the motion of the Earth orbiting the Sun. The orbit is not a perfect circle and the speed of the Earth orbiting the Sun is not constant. Through out a year there are days that are slightly more than 24 hours and there are days that are slightly less than 24 hours. There are more. There are days when both the sunrise and sunset are early. And there are days when both the sunrise and sunset are late. These lead to the equation of time.
The Sun does not always exactly rise from the east and set to the west. Through out a year its path declines northward and then southward, and then back again. This is due to the tilting of the Earth's polar axis. Hence, from an observer point of view at noon facing south or north the Sun angle is not the same through out the year. This is known as the declination of the Sun. It is contributing to the longer or shorter days and nights through out a year. Hence, it determines the actual times of sunrise and sunset which are gradually shifting back and forth through out a year.
The Sun appears to be oscillating on all axes of the Earth.
To know the position of the Sun anywhere on the Earth at any given time we need to calculate the declination of the Sun and the equation of time. See the details in Wikipedia. The calculation is based on Julian day.
If the Earth rotation is in the perfect 24 hours and the Sun always rises from the East and sets to the West then given any angle of the Sun on the solar disc we can easily calculate the time. Hence, the calculation of the prayer times will be easy and we don't have to do it every day because it will be the same every day. However, the reality is different. We have to factor the declination of the Sun and the equation of time in our calculation and we have to calculate the prayer times every day.
Apart from prayer times, the codes to calculate the position of the Sun can be used for other purposes such as a device to track the Sun, or a controller that works based on the exact day and night times. I have tested the C codes to run perfectly in ESP8266.
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