RE: mean time

[R.Hooijenga]

Noam,   actually, in a way, the equation of time curve _is_ symmetric around zero.   If you add the values of the EOT for all the days in a year, you get zero. You might say the integral of the EOT curve equals zero.   So the answer might be: legal noon was chosen such that the equation of time is, on average, zero.   Rudolf    Van: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] Namens Noam Kaplan Verzonden: vrijdag 10 juni 2005 20:43 Aan: sundial@rrz.uni-koeln.de Onderwerp: mean time Does anyone know how mean time is set up?   To clarify, I know that local mean time has 24 hours every day set for a mean daily rotation for any particular location. I understand that timezones are set up by the local mean time for the center of every 15 degrees of  longitude, i.e. 0, 15, 30, 45 etc.   What I don't understand is how was it chosen when 12:00 AM/PM would be. I used to think that mean time was set by the equinox that midday was 12:00 for the whole year. This is obviously incorrect as the equation of time which shows how much local mean time is off from apparent solar time is not 0 at 12 on the equinox.   If anybody can explain to me what and how mean time was set up, I would appreciate it.   Thanks, Noam Kaplan N 40.5833   W 74.1166 Staten Island