A comment in Patrick's latest editon of News reminded me of a discussion I recently had with a non-astronomically-inclined acquaintance. Like many people, he abhored Daylight Savings Time, seeing it as an arbitrary fiction of convenience. His reasoning centered around the idea that "it should be noon when the sun is highest in the sky". I conceded that while that idea sounded good, even under Standard Time it only happened if you by chance lived right-on the central meridian of your time zone. If you live at the western or eastern extreme limit of the time zone, the sun is still far from it's highest point- and the borders of those time zones are highly erratic and arbitrary in places. Salt Lake is about 28 minutes off of the central meridian for Mountain Time, meaning even when not on Daylight Saving time, the sun is still about 1/2 hr. away from it's highest point in the sky at noon. An extreme example in the US would be a person living in western Texas, where the sun can be up to an hour off the local meridian at noon, even on Standard Time. In places the Central time zone is well over an hour wide in terms of longitude, as is the Eastern zone in the northern U.S. and southern Canada. And even with that, there are other complications... Standard Time zones were introduced world-wide in 1884. Before then, people used "Apparent Solar Time", or true sun time, which is governed by the passage of the sun across the sky. This is the time reckoned when one reads a sundial, for example. If the sun happens to be right on your LOCAL meridian, then it is exactly noon Apparent Solar Time. Mean Solar Time is an averaged time obtained by dividing 365 days of equal length by all the time in a year. An averaged type of time, it is governed by the "mean sun", and the difference between the apparent (real) sun and the mean (average) sun ranges from zero to about 16 minutes. This correction is sometimes incorporated into your better sundials and sometimes referred to as the "equation of time". A lucid explanation of this difference can be studied at: http://www.sundials.co.uk/equation.htm The notation of time passage (as opposed to merely repetitive and cyclical events) is a strictly human artifact and has no analogy in nature. In fact as we all know, time passes at different rates depending on one's velocity relative to other objects in the universe. Any system of measurement, therefore, is valid as long as it functions reasonably well, and has a working concensus. And I must say I hate sunset at around 5 p.m. for weeks every winter. __________________________________ Yahoo! FareChase: Search multiple travel sites in one click. http://farechase.yahoo.com