Date: Tue, 3 Jan 2006 10:22:08 +1100 From: Peter Jeremy <PeterJeremy@optushome.com.au> To: Poul-Henning Kamp <phk@phk.freebsd.dk> Cc: current@freebsd.org Subject: Re: FreeBSD handles leapsecond correctly Message-ID: <20060102232208.GC42228@cirb503493.alcatel.com.au> In-Reply-To: <80965.1136240851@critter.freebsd.dk> References: <20060102221948.EBE475D09@ptavv.es.net> <80965.1136240851@critter.freebsd.dk>
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On Mon, 2006-Jan-02 23:27:31 +0100, Poul-Henning Kamp wrote: >Interestingly, the main reason why calendar reform is a no-talk >issue seems to be that The Vatican owns the standardization area >of calendars because they have written all (relevant) standards for >the area in the past. Actually, the Vatican has only been responsible for one variant of the Western calendar (the Gregorian). The Julian calendar predates the Christian church. The Vatican was open to calendar reform at the time because trying to combine elements of both Lunar and Solar calendars with a relatively inaccurate year length meant that Easter was heading for Christmas - which was felt to be undesirable. The actual algorithm was not developed within the Vatican but was promulgated by the Vatican because it was about the only international body which more than one or two countries would actually take any notice of - and even so, it wasn't until the 20th Century that (eg) Russia switched. Islam has its own calendar (with a particularly painful Leap Year calculation that gives very marginally more accuracy than the Gregorian). I'm not sure how the Chinese, Hindu, Japanese and Jewish calendars handle leap years. (I think that covers the major non- Gregorian calendars). >According to one insider, none of the possible owners of a new >calendar (ITU, ISO & BIPM) can bring it on themselves to ask the >pope permission to take over the area. The Gregorian algorithm is reasonably accurate - I think it's good for about 1 day in 3000 years. I don't know how this compares to the magnitude of miscellaneous perturbations in the Earth's orbit but it's likely to be a couple of thousand years before a further adjustmens is necessary. The obvious solution is to shift the Earth's orbit slightly towards the Sun to provide an even 365 day period. To make things even simpler, move the Earth a bit further to give a 360 day period and move the moon a bit further away to give a 30 day period. (Of course the downside of the latter change is that solar eclipses would become even rarer and might even disappear totally). With a bit of tweaking of the Earth's rotation, the need for leap seconds can also be removed. -- Peter Jeremy
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