Sunlit Design > InfoSearch > True Time (Solar Time or Apparent Time)
Index: A-D, E-R, S-Z
A
- Accuracy of Sundials
- A.D. Years
- Altitude, Solar
- Angle above Horizon, Solar
- Apparent Time
- "Astronomical Algorithms"
- Astronomical Calculations, Time Basis of
- Azimuth, Solar
- Daylight Saving Time
- Declination, Solar
- Degrees, Minutes and Seconds
- Degrees of Rotation
- Dynamical Time
True Time (Solar Time or Apparent Time)
Our concepts of time are based on an earth centred (geocentric) view of the motion of the sun.
True time is based on the motion of the physical sun around the earth. The movement of the sun around the earth is non-uniform. The sun's apparent (or true) motion varies due to:
- the elliptical nature of the earth's orbit,
- the inclination of the axis of the earth's rotation, and
- the perturbations of the moon and the other planets.
The difference between True Time and Mean Time is called The Equation of Time.
Calculate it!
The Sun API's sdxEOT function gives you the ability to calculate the amount of time that must be added to mean time to get true time.