msb@dciem.UUCP (Mark Brader) (11/18/86)
I am reposting to sci.astro an article originally sent to comp.lang.c, in the hope that one of the gurus there may lay this argument to rest once and for all, whereupon, perhaps, we can make it an Answer To a Frequently Asked Question. Many references say that, in the Gregorian calendar, century years are leap years if and only if they are multiples of 400. Some people say that multiples of 4000 are nevertheless not leap years. Now (see below) an authority has been found to support THAT statement. I am asking: * Is there in fact any particular authority that is generally agreed to be responsible for this today? After all, the Gregorian calendar was originally promulgated by the Roman Catholic Church; and most of us on this continent use it because the British government adopted it in 1752; but neither body is governing us now. * If there is such an authority, what leap year rule do they give? If not, what leap year rules do various authorities give? * Is this another case such as the question, "What do you call the year before 1 AD?", where astronomers say "0" and historians say "1 BC"? I have posted this to sci.astro only, but I am directing followps to comp.lang.c only, as that is where the question originated. Well-informed responses only, please! End of prefatory text by Mark Brader; original article by Roy Mongiovi follows. In article <54@vianet.UUCP>, devine@vianet.UUCP (Bob Devine) writes: > In article <267@bms-at.UUCP>, stuart@bms-at.UUCP (Stuart D. Gathman) writes: > > The years 4000, 8000, . . . are not leap years! > > I, too, was certain that I had read years divisible by 4000 are > not leap years. However, after several people replied with "are > you really sure?" letters, I checked. My findings were that it is > likely that someone did once make that suggestion but it has never > been formally agreed to. I never found my recollected source. In the book "ASTRONOMY" by Franklyn M. Branley (Astronomer Emeritus, The American Museum - Hayden Planetarium), Mark R. Chartrand III (Chairman, The American Museum - Hayden Planetarium), and Helmut K. Wimmer (Art Supervisor, The American Museum - Hayden Planetarium), on page 412 while discussing the Gregorian Calendar it states: "At the present time the intercalation procedure is as follows: all years divisible by 4 are leap years, except century years which are leap years only when divisible by 400. Exceptions are the years 4000, 8000, 12 000, and so on, which are not leap years." I would have thought that the authors would have known if the "multiple of 4000" rule had not been adopted, but who knows. Where is this sort of thing "officially" recorded? -- Roy J. Mongiovi Systems Analyst Office of Computing Services Georgia Institute of Technology Atlanta GA 30332. (404) 894-4660 ...!{akgua, allegra, amd, hplabs, ihnp4, masscomp, ut-ngp}!gatech!gitpyr!roy