The Vernal Equinox
As explained in the Talmud, there is a tradition that the Sun was created in its vernal equinox position at the beginning of the springtime Jewish lunar month of Nissan. The sages of the Talmud settled disputes over the halachic definition of the vernal equinox by establishing it on March 25 of the Julian calendar. Because both the Julian calendar and Jewish tradition define a solar year as exactly 365.25 days, the halachic vernal equinox historically fell out on March 25 every year. This halachic equinox now falls about 17 days after the true equinox, with the error increasing by about 3/4 of a day per century.
In summary, Birkat Hachama is recited when the halachic vernal equinox (the position at which the Sun was created) occurs at sundown on a Tuesday (the time at which the sun was created).
Read more about this topic: Birkat Hachama
Famous quotes containing the word vernal:
“Some people are like ants. Give them a warm day and a piece of ground and they start digging. There the similarity ends. Ants keep on digging. Most people don’t. They establish contact with the soil, absorb so much vernal vigor that they can’t stay in one place, and desert the fork or spade to see how the rhubarb is coming and whether the asparagus is yet in sight.”
—Hal Borland (1900–1978)