Easter is the first Sunday after the first full moon in spring. I always assumed Passover was set along the same lines – since the first Easter fell on a Passover weekend; and they always seem to land near each other every year.
But this year Easter is March 27, and Passover is April 24. What gives?
(It seems to have thrown ABC-TV off, too. They always show The Ten Commandments every year at this time. It’s on tonight – even though it has nothing to do with Easter, and everything to do with Passover.)
The Jewish calendar is lunar, so it drifts more and more out of synch with the Gregorian solar calendar each year. A leap month is added every few years to resynch with the solar cycle.
For what it’s worth, I think this year Passover is as late as it can ever be relative to the solar cycle; the last day is May 1, something I can never remember happening ever before.
I’m assuming the whole Golden Number thing has to do with how the solar and lunar years are matched up within the Jewish calendar, although I don’t exactly understand their explanation. The solar and lunar years are synched, unlike in the Muslim calendar, because the Torah specifically mandates that Passover be in the spring. This means that the month of Nisan has to always remain in the spring rather than cycling around the calendar like the months of the Islamic calendar. (I’ve always felt bad for Muslim friends when Ramadan is in the summer.) There’s a nineteen year cycle, seven years of which are leap years (13 lunar months, like this year) and twelve of which are regular (12 lunar months). Today, for example, was both March 19 on the Gregorian calendar and the 8th of Adar II (because it’s a leap year; the leap month is added after the regular Adar, and is called Second Adar) on the Jewish calendar. 19 years from now, the two dates will fall out on the same day again. (My nineteenth birthday was the first time that my Hebrew and English birthdays were on the same day, and the next time will be when I turn 38.)