Apparent solar time

Definition

Apparent solar time is a method of measuring time based on the actual position of the Sun in the sky, as observed from a specific location on Earth. It reflects the true solar noon when the Sun reaches its highest point in the sky.

5 Must Know Facts For Your Next Test

1. Apparent solar time varies slightly throughout the year due to Earth's elliptical orbit and axial tilt.
2. It is measured using a sundial, which casts a shadow to indicate time based on the Sun's position.
3. The difference between apparent solar time and mean solar time is called the equation of time.
4. Apparent solar noon occurs when the Sun crosses the local meridian and is at its highest altitude in the sky.
5. This method of keeping time was historically used before more precise mechanical clocks were developed.

Review Questions

Related terms

Mean Solar Time:

A method of measuring time that averages out variations in Earth's orbit and axial tilt, resulting in a uniform standard.

Equation of Time: The difference between apparent solar time and mean solar time, varying over the course of a year.

Sundial: An ancient instrument that measures apparent solar time by casting a shadow with a gnomon.