Re: How long is a day.....really?

[fer j. de vries]

Hi Charles,   What is a day????????????   My watch says any day is 24 hours long. ( Many watches say 2 x 12 hours, but that's also 24 ) These are regular hours, all of the same length.   My sundial ( for suntime ) also says any day is 24 hours long. But these are irregular hours, the length of an hour changes. ( however I won't notice it if I don't use my watch ). This is because my sundial defines a day in another way. If the sun is South or North the day starts and the day ends if the sun is at the same position again.   Thus any day is 24 hours long, but measured in 2 time systems.   Now I use the sundial's day and meausure it length with my watch. The result is that I get a difference, the famous EoT. And then a day is 24hours and 30 seconds around Christmas.   I didn't look up for the values at the equinox or the solstices, I am too lazy for it......... So I leave the exact answers to your question to you............   What a nice stuff, isn't it?   However, it is even more complected nowadays. The timesystem of our world counts something of an atom and that's atomic time. It's very regular and very presize. Its precision is so high that from time to time we add a leap second to the atomic time to set our watches. Only with this artificial added seconds we keep the time of our watch in some relation to the sun. Some days aren't 24 hours watch time, but sometimes a day is 24 hours and 1 second watch time.   Conclusions : the day in our precize world is sometimes of different length, thus irrigular. the day in sundial time always is 24 hours, thus regular.   Shouldn't we go back to sundial time? We never need to add a leap second to our watch.................   Best wishes, Fer.     Fer J. de Vries [EMAIL PROTECTED] http://www.iae.nl/users/ferdv/ Eindhoven, Netherlands lat.  51:30 N      long.  5:30 E ----- Original Message ----- From: Charles Gann To: Sundial List Sent: Tuesday, July 04, 2000 6:20 AM Subject: How long is a day.....really? Ponder this one!   On the calendar day of an equinox, from the moment that day first pops into existence somewhere on the earth, to the moment it winks out of existence, how long does it exist?   How long does it exist at the solstices?   Charlles