> > Keep the leap second, no leap hour. The systems of time are rather complicated, and one cannot discuss it with simple arguments without knowing all details. As a staff member of the Central Bureau of the International Earth Rotation and Reference Systems Service and member of the IAU working group on the future of UTC, and also as historian of astronomy and person interested in sundials I have thought much about this problem. I cannot explain all problems in detail here, but I will try to mention some important points:
1. The introduction of the leap seconds at irregular and unpredictable moments of time and the existence of a discontinous time scale bears a lot of technical problems. That's why the GPS system does not use UTC but introduced its own time scale, running in parallel to Atomic Time TAI. There are very good arguments against leap seconds. 2. Our watches do not show UTC (except in Great Britain in winter). And, as you know very well, they do not display true solar time. Therefore, sundials only in very exceptional cases show the same time as normal watches. Our watches display zone time + (half of the year) 1 h. In summer time, this may differ from local time by 1 1/2 h or more, in Russia by 2 1/2 hour or more, and in China by several hours. You have a "leap hour" twice each year when summer time starts or ends, and you have a "leap hour" whenever you enter the next time zone when travelling. UTC is used in scientific and technical applications, not in every-day life. The keep the time which is displayed by our watches more or less connected to earth rotation, one can easily adopt the zone time. 3. There is a time scale which is really following earth rotation: UT1. This will be kept, and IERS will start a time service by transmitting (details have to be fixed). So, whenever you need a clock which displays time connected to earth rotation (e.g., for pointing a telescope), you may use UT1. To see some of the definition for leap second, UTC, TAI, UT1, I may recommend the IERS Glossary at http://www.iers.org/iers/earth/glossary/ and the links therein. Best regards, Wolfgang Dick -
