Equation of time is the difference between apparent solar time and mean solar time. EOT = apparent solar time – mean solar time Wikipedia defines EOT by the follwoing: The equation of time describes the discrepancy between two kinds of solar time. The word equation is used in the medieval sense of “reconcile a difference”.… Continue reading Equation of Time

# Category: Solutions

## Sun Right Ascension

Wikipedia defines Right ascension (RA) as the angular distance of a particular point measured eastward along the celestial equator from the Sun at the March equinox to the (hour circle of the) point in question above the earth. When paired with declination, these astronomical coordinates specify the location of a point on the celestial sphere… Continue reading Sun Right Ascension

## Islamic Prayer Times

Moslems Must Observe the apparent movement of the sun across the sky in order to performs prayers. There is no consensus on the times of the prayers among different Moslem factions and developing an algorithm was affected by this fact. For example, Sun depression angle considered to calculate Fajr and Isha prayers are not agreed… Continue reading Islamic Prayer Times

## Directions On Map

The direction between any two places on Earth can be calculated using the spherical trigonometry. We can use the following equation to do that Direction Angle =tan-1 (sin(longitude2 – longitude1)/cos(latitude1)*tan(latitude2)-sin(latitude1)*cos(longitude2-longitude1)) In spherical trigonometry values of latitude and longitude represent angles as in the following diagram: Example One famous example is The Islamic Qibla. Muslims need… Continue reading Directions On Map

## Calculating Sun Declination

Declination of the sun is the angle between the equator and a line drawn from Earth to Sun center to center. The declination angle varies seasonally due to 2 factors — the tilt of the Earth on its axis and its rotation around the sun. If the Earth were not tilted on its axis of… Continue reading Calculating Sun Declination

## Calculate Sunlight Hours

The duration of sunlight follows a simple harmonic motion. It is periodic and repeats every year. In the Northern Hemisphere, the longest day is June 21, and the shortest is December 21. The averagelength of daylight is 12 h, and the variation from this average depends on the latitude. (Forexample, Fairbanks, Alaska, experiences more than… Continue reading Calculate Sunlight Hours

## Julain Day Calculation

How To Calculate the Julian Day These are the steps: let a = (10000.0 * year) + (100.0 * (month)) + day; note: a should be > -47120101 If month <= 2 then add 12 to month to become 13 or 14 and substract 1 from year let b1 = Floor(year / 400)… Continue reading Julain Day Calculation