The Jewish calendar is a lunar one, but it is coordinated with the solar one so that our holidays don't drift seasons. This is done with a complicated 19-year-cycle where there are leap years that insert an extra month rather than an extra day as in the secular year. So once every 19 years, each individual's Hebrew birthday aligns with his/her secular one (or close to it - those secular leap years sometimes throw it off by a day). But I digress - that wasn't what I was going to write about.
Back to Birchat Hachama - it is a special blessing said once every 28 years. According to tradition, the sun is in the same position it was in when it was created then and the blessing praises G-d "who makes the works of the beginning" (i.e. the first creations). In 1897 a rabbi in NYC who was leading a group saying the blessing in Tompkins Square Park was arrested for not having a proper permit, as described here.
I do the weekly flier for my shul and here's what I wrote about Birchat Hachama for this week's flier:
Here Comes The Sun
On Wednesday morning, April 8, 2009 we’ll have an opportunity to do something we last did when Ronald Reagan was president, before the internet was created, when Pluto was still a planet, before reality TV or rap, while the proof of the Four Color Map Theorem was still in dispute, when Nunavut was still part of the Northwest Territories and Ukraine was still preceded by the definite article, before a whole lot of PSJC-er’s were born! Birchat Hachama is the blessing of the sun said once every 28 years, at the time when our tradition says our sun is in the same position it was at the time it was created. Even if you don’t usually come to Wednesday morning minyan, take a little time out of Pesach prep and join us at 7:15. You won’t get another chance until April 8, 2037.