I don't want to rain on your sun blessing, but the whole thing is a fraud. We aren't celebrating the moment of the sun's return to the original spot of creation. We're celebrating an arbitrary date, chosen by a gentile, and embraced by Jews selectively and for the sake of convenience.
This blog does not wish to bore you, so I'm going to skip the math and be brief:
Based on a line and a half in Brachos 59B, we say the sun blessing when the vernal equinox coincides with Tuesday night. If you suppose that (a) a tropical year is 365.25 days, and (b) that the very first-ever vernal equinox corresponded with March 25 some fancy math will yield a 28 year cycle, which concludes again on April 8, 2009.
However, (a) a tropical year is not 365.25 days and (b) the vernal equinox, per our current calendar, always occurs on March 20, or 21.
See the problem?
How this mess was made is complicated, and involves (1) the Julian Calendar, upon which the calendar of Mar Shmuel was based; (2) the switch to the Gregorian calendar, a switch that was was not recognized for the purpose of calculating Birchas Hachama; and (3) the original decision to date the equinox on March 25, which, so far as I can tell, was a mistake made by Ceaser and his gentile astronomers (corrections welcome).
The upshot, unfortunately, is this: Our sun blessing this Wednesday will not correspond with any astronomical event.
And what of the precious idea that Birchas Hachama is a celebration of the moment when the sun returns to the spot where it was created?
Well, bad news, but that's bogus. too.
According to Jewish tradition, the sun was created at the vernal equinox. I don't know when this idea entered the Jewish imagination, but fine: call it mesorah. Unfortunately, it can't be true that April 8, 2009 is the day of the sun's return to its original spot, and here's why:
(a) the vernal equinox was two weeks ago on March 21
(b) the idea that April 8 marks the day of the sun's return to its original spot it based on the supposition that a year is 365.25 days. This is wrong.
(c) Even if the supposition was correct, the completion of the cycle would not occur on April 8, but at 6 PM on April 7.
So, what's so special about April 8? I'm no longer sure.
NOTE: Some of this information has appeared previously at Ben Chorin and I expect some is also in the Hirhurim blog book which I have not read. If its on your blog, too, tell me and I'll gladly link you up.
Update: Many bloggers who have written about this subject have left links to their posts in the comments. Please click the links, and visit those blogs!
Update 2: As I suspected, the contents of this post are discussed at length in the Hirhurim blog book.