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