View Full Version : How is sunrise determined?

2003-Apr-08, 01:25 PM
:D I wonder if you could help? I hope I don't appear too foolish.
I am studying acupuncture and the topic of energetic movement. This study brings into question the clocked times that the Chinese used to measure Chi energy movements through our bodies. This is my first look into the subject In my understanding, the Chinese used a "Ke" measure that divided the 24 hr day into 100 parts,Ke's. The charts then divide the flow of energy based on this premise. My instructor also theorized that based on information from the ancient text "the Ling Shu" he can postulate that the noon hour is when the sun is directly overhead and that this is truly mid day. Therfore the chart has to be adjusted based on the time of sunrise Based on this concept we take the time of sunrise and sunset and count the number of daylight hours and divide that in half and add that number to the sunrise time to arive at the hour "that is true noon", then we subtract or add the time difference to adust our watches accordingly. This will allow us to maximize our treatment based on utilizing the natural cycle and flow of Chi.
I would be interested in your perspective of this varriation of noon from the chinese Ke system. Also I have experienced much confusion trying to find out when sunrise and sunset occur. Each source of internet weather stations don't seem to agree, they seems to have different times posted for sunrise and sunset. When I was in the mountains last month, I joked that sunrise would depend on which side of the mountain you stood at, my joke seems to have taken on life. How can I know which souce is correct?

2003-Apr-08, 02:16 PM
The time of sunrise and sunset depend on your EXACT position, so for starters you need a computation that includes your position. The math to calculate the times is pretty involved so find yourself a piece of astronomy software (astronomy lab for windows is decent) to do it for you.

Also, the sun is rarely directly overhead, noon is when the sun is at its highest.

2003-Apr-08, 05:43 PM
Sunrise/sunset depend on geographical details (mountains in the east will delay sunrise). Most programs won't account for that. But they may account for refraction, and i think refraction would retard sunset more than it would advance sunrise.

Most programs that give sunrise/sunset times would also give the time when the sun reaches the zenith, which is i think what you really want.

There's some ambiguity involved here, i suppose. Maybe you could set up a double blind experiment and determine which means of calculating noon is most effective. Among your choices would be (1) clock time (after all, people's lives are ruled more by the clock than by the sun) (2) GMT (3) local sun time with zenith as noon (4) local sun time with midway between sunrise and sunset as noon (5) Peking sun time with zenith as noon (6) Peking sun time with midway between sunrise and sunset as noon. (Peking times included because i believe the Chinese astrologers viewed Peking as the center of the Universe). I suppose you could also try some variants of sidereal time (maybe energy flows are more associated with Sirius than the Sun). If there is a trend for remedies to be more efficacious at various times of the year you might look into that.