Statements so far - disgree or add please (in particular something on UT1/UT/etc as I will only get it wrong...):
General: - the terms seconds, minutes, hours and days are overloaded, thus pedantic and explicit terms are used here SI - the SI-second is a standardised unit of measurement - the SI-second is currently defined as a fixed number of transitions of a caesium atom - the current definition of the SI-second was ratified in 1967 - an SI-based-minute is formed from exactly 60 SI-seconds - an SI-based-hour is formed from exactly 60 SI-based-minutes and thus exactly 3600 SI-seconds - an SI-based-day is formed from exactly 24 SI-based-hours and thus exactly 86400 SI-seconds Solar - a solar-day is a measured period of time - the length of a solar day in in SI-seconds varies over time - the length of a solar day in in SI-seconds is on average increasing with time - a solar day is not a fixed number of SI-seconds - a solar-hour is the period of 1/24th of a single measured solar-day - a solar-minute is the period of 1/60th of a solar-hour and thus 1/1440th of a single measured solar-day - a solar-second is the period of 1/60th of a solar-minute and thus 1/86400th of a single measured solar-day Humanity - a humanity-day is a non-scientific, commonly used term understood by 6bn humans - a humanity-day is interpreted in line with the rising and setting of the Sun TAI-2011 - the TAI-2011 time-scale is known as TAI in the year 2011 - the TAI-2011 time-scale is defined as a uniformly increasing count of SI-seconds from a fixed epoch UT-2011 ??? UT1-2011 ??? UTC-2011 - the UTC-2011 time-scale is known as UTC in the year 2011 - the UTC-2011 time-scale is a continuous count of SI-seconds - the UTC-2011 time-scale defines UTC-2011-days - a UTC-2011-day is either 86400 SI-seconds or 86401 SI-seconds long - the additional SI-second in a UTC-2011-day is a leap-second - the presence or absence of a leap-second is determined up to 6 months in advance Lets see, how we go on these... Stephen _______________________________________________ LEAPSECS mailing list [email protected] http://six.pairlist.net/mailman/listinfo/leapsecs
