Rob Seaman wrote: >Apparent solar time is derived from mean solar time, not the other way >around.
The way I see it, apparent solar time is, in an astronomical sense, derived from sidereal time, not from mean solar time. Apparent solar time is just sidereal time minus true anomaly. All three parts of this equation are astronomically reified angles: they could be measured directly given a protractor and a suitable viewpoint. Mean solar time, on the other hand, does not correspond to any actual geometric angle. It can't be measured directly from the instantaneous positions of the bodies. Mean solar time is sidereal time minus mean anomaly, but the mean anomaly is a mathematical construction, not a direct part of the geometry. Granted, the concept of mean solar time can be applied without requiring the kind of human activity that is inherent in timezones or TAI. In that sense it's a naturally-occurring time scale. But it's no more fundamental than apparent solar time; if anything, it is less so. Of course, for the purposes of human psychological factors, the (periodic) difference between mean solar time and apparent solar time is insignificant. An unaided human would be hard pressed to distinguish between them. -zefram _______________________________________________ LEAPSECS mailing list [email protected] http://six.pairlist.net/mailman/listinfo/leapsecs
