Birkat Hachama is observed by Judaists and Jews which only occurs every 28 years solar cycle known as "Machzor Gadol" ( , "the great cycle").
The blessing is recited when the sun completes its cycle every 28 years on a Tuesday at sundown. Judaism and Jews According to Judaism, the Sun has a 28-year solar cycle known as machzor gadol ( , "the great cycle"). 
