Hihi, I am back with Equations, I was going to do sundials but please...it's extremely boring. So I think this bit better. LOL.
Sundials give you apparent solar time.
Ou rmodern clocks give us the mean solar time.
Sometimes the apparent solar time is either shorter or longer than the mean solar time, this is because Sun motion in respect to the background stars change often throughout the year.
The difference between apparent solar time and mean solar time is apparent solar time.
•Equation of time = apparent solar time - mean solar time
The equation of time is positive when the sundial is fast, and it's negaive when is sundial is slow.
•Only on 4 days each year will an accurate sundial and an accurate clock give the same time: April 15, June 15, September 2 and December 25.
There are two effects that arises the equation of time.
Earth is near perihilion in January so its orbital period is higher, Earth has to turn a little more than the average angle for the Sun to reach it's meridian, so the sundial is slow and the equation of time is negative,
In July Earth is near aphelion, so the orbital period is slower, Earth has to turn a little less than the average angle for the Sun to reach it#s meridian, so the sundial is faster and the ewuation of time is positive.
Motion of Sun along ecliptic rather than celestial equator
•But only motion parallel to celestial equator causes variation in length of solar day
•Results from tilt of Earth’s axis with respect to ecliptic plane (obliquity)
THAT'S IT!!! YEH..NOW WASN'T THAT EASY??
_____________________________________________
Simplicity is the ultimate sophistication. Leonardo da Vinci
Sundials give you apparent solar time.
Ou rmodern clocks give us the mean solar time.
Sometimes the apparent solar time is either shorter or longer than the mean solar time, this is because Sun motion in respect to the background stars change often throughout the year.
The difference between apparent solar time and mean solar time is apparent solar time.
•Equation of time = apparent solar time - mean solar time
The equation of time is positive when the sundial is fast, and it's negaive when is sundial is slow.
•Only on 4 days each year will an accurate sundial and an accurate clock give the same time: April 15, June 15, September 2 and December 25.
There are two effects that arises the equation of time.
Earth is near perihilion in January so its orbital period is higher, Earth has to turn a little more than the average angle for the Sun to reach it's meridian, so the sundial is slow and the equation of time is negative,
In July Earth is near aphelion, so the orbital period is slower, Earth has to turn a little less than the average angle for the Sun to reach it#s meridian, so the sundial is faster and the ewuation of time is positive.
Motion of Sun along ecliptic rather than celestial equator
•But only motion parallel to celestial equator causes variation in length of solar day
•Results from tilt of Earth’s axis with respect to ecliptic plane (obliquity)
THAT'S IT!!! YEH..NOW WASN'T THAT EASY??
_____________________________________________
Simplicity is the ultimate sophistication. Leonardo da Vinci
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