Re: Year 2000 Issue

["Otto G. Raabe" <ograabe@ucdavis.edu>]

At 08:34 AM 6/10/97 -0500, Ron Amoling wrote:
>Nothing personal, but it is clear that nobody here has a clue as to 
>what the leap year status of year 2000 is.  For every person who 
>states factually that there is a leap year, there is another who 
>states there is none.
>
>Let's not waste any more time discussing something about which we do 
>not know!
>
>Like one radsafer said simply.....READ AN ALMANAC, then decide for 
>yourself if there's a leap year or not!

Although three people made short incorrect comments on RADSAFE suggesting
that the year 2000 is not a leap year, seven (many substantive) messages on
RADSAFE proved and explained why it is!

6/5/97 C. Hawkins commented that "EXCEL works for year 2000 "but adds the
illegal Feb 29, 2000." [WRONG, not illegal]

6/5/97 D. Haes asks "What's illegal about Feb 29, 2000?" [CORRECT]

6/5/97 P. Hill commented "2000 has no Feb. 29" based on century rule. [WRONG]

6/5/97 C. Bodily said "centuries don't have a leap year -- unless the
century is divisible by 4 (actually 400). So there is indeed a Feb. 29 in
the year 2000." [CORRECT]

6/5/97 C.Koch provides a history of the Gregorian calendar and explains that
"2000 will be a leap year since 2000 is divisible by 400." [CORRECT]

6/7/97 L. Fraley used the incomplete division by 4 rule to say "There is no
29 Feb 2000." [WRONG]

6/7/97 O. Raabe explains why "There will be a February 29, 2000." [CORRECT]

6/8/97 S. Frantz agrees with Raabe that "there will be a Feb. 29, 2000."
[CORRECT]

6/9/97 B. Cohen explains correctly why "There will be a Feb 29 in 2000."
[CORRECT]

6/9/97 D. King agrees about whether there is a Feb. 29, 2000. "Yes there
is." [CORRECT]

6/9/97 O. Raabe provides an elaborate explanation on leap year rules and
their basis and explains why "There will be a February 29, 2000." [CORRECT]

6/10/97 R. Amoling writes: "it is clear that nobody here has a clue as to 
what the leap year status of year 2000 is.  For every person who 
states factually that there is a leap year, there is another who 
states there is none." He recommends "Decide for yourself if there's a leap
year." [?]

Well Ron, the vote is apparently 7 to 3 in favor of a leap year, but the
important issue is discriminating between fact and error. Hopefully,
radiation safety specialists are good at that. Here again are the facts:

Years that are evenly divisible by 4 are normally leap years unless they are
also evenly divisible by 100, in which case they are not leap years unless
they are also evenly divisible by 400. Hence, per 1,000 years there will be
365,242.5 days with this system. 

Although 1900 was not a leap year, the last year of the 20th century, the
year 2000, will be a leap year. There will be a February 29,2000.

Leap years are necessary because of the time required for the earth to move
around the sun with respect to their relative positions. The tropical year,
which keeps the seasons in their right places, is defined by the time for
two consecutive returns of the sun to the vernal equinox (at the earth's
equator). That is 365 days, 5 hours, 48 minutes, and 46 seconds in 1990
(1997 World Almanac). It is decreasing by about 0.530 seconds per century.
Hence, the tropical year is now about 365.2422 days. With the leap year
system, there is an extra 3 days every 10,000 years. That's about an extra
26 seconds per year. We could approximately correct by not allowing years
divisible by 4,000 to be leap years. Luckily, we have astrophysicists and
atomic clocks to help keep us on time. 

Although 1900 was not a leap year, the last year of the 20th century, the
year 2000, will be a leap year. There will be a February 29,2000.

I hope this is all there is on this issue. 

Best regards,

Otto
		*****************************************************
		Prof. Otto G. Raabe, Ph.D., CHP
		Institute of Toxicology & Environmental Health (ITEH)
		     (Street address: Old Davis Road)
		University of California, Davis, CA 95616
		Phone: 916-752-7754     FAX: 916-758-6140
		E-Mail: ograabe@ucdavis.edu
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