The moon circles our earth each month. In the course of each cycle, there is a moment when the moon lines up between the earth and the sun. This astronomical configuration is termed “new moon.” At that point, the moon is not visible from the earth nor will it be until 18 to 30 hours later.
During 2014, the new moon nearest the vernal (spring) equinox will be on March 30, at 8:45 p.m. (20:45), Jerusalem time. The following sunset in Jerusalem (March 31) will come about 21 hours later. It is doubtful that the first sliver of the moon will be visible then. More likely, the first sunset when the initial crescent of the moon can be seen in Jerusalem will be on April 1. By the method the ancient Jews used, that will be the day when the first month (Nisan 1) will start, at sunset.
Hence, congregations of Jehovah’s Witnesses around the earth have been informed that Nisan 14 will begin at sunset on Monday, April 14, 2014. That will be about the time of the full moon.—For more details on calculating the date, see The Watchtower of June 15, 1977, pages 383-384.