Every 28 years, the ritual is performed. It's a blessing of the sun based on it's return to the exact position it was in when the sun was created by God. (pretty amazing calculation!!)
I read about this too Supposedly it is in the same position as it was on the 4th day of creation.
In ancient days, the Isrealites had some pretty advanced astronomical knowledge, especially considering that they did not thing of the stars as reflections of divine beings, but rather as the creations of the one-divine being.