|The event Birkat Hachama or Blessing on the Sun occurs once every 28 years. But it has only ever occured on this exact date on the Hebrew calendar, the 14th of Nissan, three times;1). Prior to the Jews escaping slavery and being redeemed from Egypt
2). Prior to the miracle of Purim
3). And in the year 6759 (now! – 2009 in the Gregorian calendar)
Once every 28 years, the Sun returns to the position it occupied when it was created at the beginning of the fourth day of creation.
And Hashem made the two great lights: the greater light to rule the day, and the lesser light to rule the night and the stars. And Hashem placed them in the sky of the heavens to give light on the earth, and to rule over the day and over the night, and to divide the light from darkness; and Hashem saw that it was good. And it was evening and it was morning, a fourth day.
Why does Birkat Hachama take place only every 28 years?
The starting point is Tuesday at 6:00 pm. Now, since a year lasts 365 1/4 days – or 52 weeks plus a remainder of 1 1/4 days – it follows that after one year, the Sun will return to the spring equinox, but will fall 1 1/4 days later in the week: Wednesday at midnight. After two years, the Sun will return to the spring equinox, but it will now be 2 x 1 1/4 days later in the week: Thursday at 6:00 am. Only after 28 years, will the Sun return to the spring equinox on Tuesday at 6:00 pm.