@S1-A.ARPA,@MIT-MC.ARPA:FRIEDRITR%VAXJ.GATNET.MFENET@LLL-MFE.ARPA (07/31/85)
From: FRIEDRITR%VAXJ.GATNET.MFENET@LLL-MFE.ARPA As was pointed out by someone else, the Gregorian calendar is still off by 26 seconds per year, even with the centuries-are-only-leap-years-sometimes adjustment. Leap seconds are not to "even out the flaws in the Gregorian calendar", especially since we have one only every few years (does anyone know how often, on the average?). Leap seconds keep our precise 24-hour- per-day clocks synchronized with the actual rotational period of the Earth, which exhibits slight variations. Terry
scott@ubvax.UUCP (Scott Scheiman) (08/05/85)
In article <2884@mordor.UUCP>, @S1-A.ARPA,@MIT-MC.ARPA:FRIEDRITR%VAXJ.GATNET.MFENET@LLL-MFE.ARPA writes: > From: FRIEDRITR%VAXJ.GATNET.MFENET@LLL-MFE.ARPA > > Leap seconds are not to "even out the flaws in the Gregorian > calendar", especially since we have one only every few years (does anyone > know how often, on the average?). Leap seconds keep our precise 24-hour- > per-day clocks synchronized with the actual rotational period of the Earth, > which exhibits slight variations. > > Terry -- Quite a few years back they came only every few years, at midnight beginning a new year. Then a year came when they added a leap second at both ends of the year. This year we had a leap second added between June and July (I think). I don't know why it was added in the middle of the year this year, but my guess is that we now have to have more than one leap second added per year and adding two on Jan. 1 (Dec. 31?) would be more disruptive than "smoothing" it out by adding them at far ends of the year. -- "Ribbit!" Scott Scheiman (Beam Me Up, Scotty!) Industrial Networking, Inc. \ /\/@\/@\/\ ..decvax!decwrl!sun!megatest!ubvax!scott 3990 Freedom Circle _\ \ - / /_ (408) 496-0969 Santa Clara, CA 95050
mojo@kepler.UUCP (Morris Jones) (08/10/85)
In article <287@ubvax.UUCP> scott@ubvax.UUCP (Scott Scheiman) writes: >Quite a few years back they came only every few years, at midnight >beginning a new year. Then a year came when they added a leap second at >both ends of the year. This year we had a leap second added >between June and July (I think). I don't know why it was added in the >middle of the year this year, but my guess is that we now have to have >more than one leap second added per year and adding two on Jan. 1 >(Dec. 31?) would be more disruptive than "smoothing" it out by adding I believe they have a stated goal of keeping Coordinated Universal Time within a second of astronomical time -- hence the scattered addition of leap seconds. I know that WWV brodcasts a correction, plus or minus seven tenths of a second or so, to correct CUT to astronomical. You count the double clicks before or after the minute mark to get the correction. P.S., Scott, I like your frog. "Time's fun when you're having flies." -- Mojo ... Morris Jones, MicroPro Product Development {dual,ptsfa,hplabs}!well!micropro!kepler!mojo
karn@petrus.UUCP (Phil R. Karn) (08/11/85)
It is true that the earth exhibits fluctuations in its rotation phase due to, among other things, seasonal atmospheric mass shifts, etc. However, I think leap seconds are needed mainly because the standard atomic second was defined to be a little too short compared to the second based on the average rotation rate of the earth. That's why we almost always seem to have extra leap (60th) seconds in UTC instead of missing 59th seconds. Phil