March 7, 2004
Many of you have asked me what happened to the www.diaperboys.com website. While I had no idea what happened to it, I am pleased to announce that the site is back up. The site address is now http://www.diaper-boys.biz (note the .biz top-level-domain). Let's hope the site will stay up and running.
I have recently received several requests (all of them polite, thankfully) from people asking to either have their email addresses removed or having their entries removed completely. The main reason for these requests is that Google and other search engines will turn up their names and/or email addresses. They either fear that their friends/families/co-workers might find them, or their acquaintances have already found them. Therefore, I am advising everyone who posts to the guestbook to use discretion when posting names and email addresses. If the option is available to you and you want people to contact you I'd recommend obtaining a secondary email address at Hotmail or Yahoo. Please also use this discretion if you decide to include your email address with story submissions.
In last week's MOTW I stated:
Leap Day, an event which only occurs once every four years in order to keep the calendar from gradually going out of whack (over the course of a century we'd be off by almost a month).
Someone astutely pointed out to me that this is not quite the case, though it would seem logical to assume that as the earth's rotation each year adds about .25 days to the time cycle, over a hundred years this would add up to about 25 days, or almost a month. A citation noting this phenomenon is at http://www-astronomy.mps.ohio-state.edu/~ryden/ast161_2/notes6.html. The pertinent information on this site appears below:
Designing calendars based on the tropical year and the mean solar days is made difficult by the ugly fact that there are 365.242199 mean solar days in a tropical year. This is not a nice whole number. If there were exactly 365 days per year, making calendars would be a piece of cake. It's those extra 0.242199 days per year that account for the complication of leap days.
The calendar that is commonly used today (the one that states that today is Wednesday, October 2, Anno Domini 2002) has its roots in ancient Rome. The Roman Republic had a 365 day calendar into which leap days were inserted by a board of priests, whenever it appeared that the calendar was out of synch with the seasons. By the time Julius Caesar came to power, the Roman calendar was badly screwed up. Caesar, in the year 46 BC, asked an Alexandrian astronomer named Sosigenes to reform the calendar. The calendar proposed by Sosigenes had 365 days in an ordinary year, but during every fourth year, an extra day (called a leap day) was interpolated. Julius Caesar accepted the recommendation of Sosigenes and instituted the new calendar. (Note that this calendar is now called the Julian calendar, not the Sosigenean calendar; an astronomer does all the work, and a politician grabs the credit.)
The Julian year is thus slightly too long; the Julian calendar was like a slow clock, lagging behind the true time, as indicated by the Sun in the sky, by 1 day every 128 years. At first, nobody cared, but by the 16th century AD, the Julian calendar was `out of alignment' by 10 days; according to the increasingly inaccurate Julian calendar, the vernal equinox was occurring on March 11 instead of March 21. This worried officials of the Christian church, since the date of Easter is tied to the date of the vernal equinox. They didn't want to celebrate Easter on the wrong day.
- Average length of year in the Julian calendar = 365.25 days
- True length of tropical year = 365.242199 days
Pope Gregory XIII announced it was high time to reform the calendar, to restore the vernal equinox to March 21 (or thereabouts) and to make sure that it stayed there. An amateur astronomer (and professional physician) named Aloysius Lilius proposed a new formula for computing when leap days should be inserted. According to Lilius, century years (that is, years whose number ends in a double zero) should NOT be a leap year unless they are evenly divisible by 400. Pope Gregory accepted the recommendations of Lilius, and the resulting calendar - the one we use today - is called the Gregorian calendar. (Note: not the Lilian calendar!) In the Gregorian calendar:
The Gregorian calendar was adopted by Catholic countries in October 1582. At the same time, 10 days were dropped from the calendar to restore the vernal equinox to March 21. England and its colonies adopted the Gregorian calendar in 1752; Russia adopted it in 1918; China adopted it in 1949.
- 1600 was a leap year
- 1700, 1800, 1900 were not leap years
- 2000 was a leap year
- 2100, 2200, 2300 will not be leap years
The Gregorian calendar will lag behind the true time, as indicated by the Sun in the sky, by only 1 day every 33 centuries. So far, since the Gregorian calendar has been in use for less than a millennium, nobody is particularly worried about the discrepancy.
- Average length of year in the Gregorian calendar = 365.2425 days
- True length of tropical year = 365.242199 days