So, what are the funky months and years for the Julian Day and Rata Die calendars!?
Both Julian Day and Rata Die formats are sequential day numbers and as such don't have
either months or years. The Julian Day and Rata Die numbers for each day on the calendar
can be see by looking at the generated URLs when hovering over each date (usually visible in the
status bar at the bottom of the browser window)
To allow display in a typical calendar format a month/year format needed to be
chosen. There were two goals: a month of around 30 days, and a format that could be relitively
easily converted to and from the standard sequential day number format. Here's what was choosen:
a 25 day month starting at day 0 and ending at day 25
a 400 month year
This then means a year is 10000 days long and the format is yyymmxx where:
yyy is the year
mm is the month
xx is broken up into a frational month and a day of the month
For example October 22, 2008 has a Julian Day number of 2454762. To convert this to a
year/month format: 245 is the year, 47 is the month, 62 is greater than 50 so the fractional month
is .5, and the day is 12. This makes the Julian Day number 245/47.5/12 in y/m/d format.
For example October 22, 2008 has a Rata Die number of 733337. To convert this to a
year/month format: 73 is the year, 33 is the month, 37 is greater than 25 so the fractional month
is .25, and the day is 12. This makes the Rata Die number 73/33.25/12 in y/m/d format.
How are the number of days until an event calculated? When we talk about the number of days until an event, we naturally round upwards. For
example, on Tuesday we say there are 2 days until Thursday. We do this even on Tuesday evening
when there are only a few more than 24 hours until Thursday begins. DaysUntil.com also rounds
upwards. This behaviour can be changed on the preferences page by changing the resolution to show the
number of hours, minutes, and seconds until the event occurs.
Rounding upwards can cause some confusion, when events do not start at midnight. For
example dates on the Hebrew calendar, such as Hanukkah, begin at sunset. On the day before
Hanukkah, DaysUntil.com will display 2 days
until Hanukkah if it is before sunset, and 1 day until Hanukkah if it is after sunset.
This behaviour is slightly different for published iCalendar files. Since the subscribers
current time of day is not known, times are ignored. The day that an event begins, no matter
what time, is considered to be the first day of the event and the day before is always shown as
1 day until (e.g. 1 day until Hanukkah will show even after sunset the day before).
Why does Christmas last two days on the Hebrew calendar - Christmas (Hebrew)? Each day on the Gregorian calendar starts and ends at midnight, not at sunset as
it does for the Hebrew calendar. This means a Gregorian day covers parts of
two days on the Hebrew calendar: from midnight to sunset, plus a few extra
hours from sunset to the next minight. So any event on the Gregorian calendar
seems to take an extra day on the Hebrew calendar because it ends a few hours late,
at midnight, on the following day. This extra time is made up at the beginning because
the event doesn't start until midnight, after the end of the Hebrew day at sunset. So,
Christmas lasts 1 day, but on the Hebrew calendar it ends at midnight on the
following day and seems to be 2 days long.
Why does Hanukkah last 9 days on the Gregorian calendar - Hanukkah (Gregorian)? Each day on the Hebrew calendar starts and ends at sunset, not at midnight as
it does for the Gregorian calendar. This means a Hebrew day covers parts of
two days on the Gregorian calendar: a few hours from sunset to midnight, and
from midnight to sunset on the following day. So any event on the Hebrew calendar
seems to take an extra day on the Gregorian calendar because it starts early
at sunset on the previous day. This extra time is made up at the end because
the event ends at sunset, before the end of the Gregorian day at midnight. So,
Hanukka lasts 8 days, but on the Gregorian calendar it starts at sunset on the
previous day and seems to be 9 days long.
iCalendar questions:
How do I subscribe to/download an iCalendar event feed? Every event category has an iCalendar event feed. The easiest way to subscribe is to click
on the icon in each category
box at the bottom left of every event. You can also download the events instead of subscribing
by clicking on the icon. There are also subscribe
and download links at the top of every category page.
How do I subscribe to/download an iCalendar countdown feed? Every event has an iCalendar countdown feed. The easiest way to subscribe is to click
on the icon at the far right
of every event. You can also download the countdown instead of subscribing
by clicking on the icon. There are also subscribe
and download links at the top of every event page.
There are several optional parameters that can also be added. To specify a parameter, you must add "/index.html?"
followed by the parameter. If you add more than one parameter, they must be seperated by an "&" (only the first
parameter is seperated from the rest of the URL by a "?").
The possible parameters are:
date - show events for a specific date
rdDate - show events for a specific Rata Die date
showCompleted - show completed events for the current month
hideCompleted - hide completed events for the current month
What is the syntax to specify a date in the URL?
The syntax is: date=Calendar[-year[-month[-day]]]
Where "Calendar" is required and is one of the following:
Gregorian
Julian
Hebrew
Julian Day
Chinese
Mayan
Islamic
Rata Die
"-year" is optional and must be for the selected Calendar. For example:
If "-month" and/or "-day" are out of their allowed range the an attempt is made to calculate the date desired. This is sometimes useful for limited date arithmetic. For example:
icon in each category
box at the bottom left of every event. You can also download the events instead of subscribing
by clicking on the 
icon. There are also subscribe
and download links at the top of every category page.