March 30 – April 5, 2015
Mt. Washington — Each year, the dates of Passover and Easter are determined by the date of the first full moon after the vernal equinox, known as the paschal moon in the Judeo-Christian tradition. Passover begins on the day of the paschal moon, whereas Easter is observed on the first Sunday following the full moon that follows the equinox.
This year the equinox was March 20. The first day of Passover is Saturday, April 4, when the moon becomes full at 8:05 a.m. E.D.T. The first Passover Seder is celebrated Friday evening the 3rd because the Jewish calendar date begins at sundown of the preceding night. Easter Sunday is April 5th, the first Sunday after the first full moon after the equinox. Before the advent of ecclesiastical calendars, the dating of these holidays was primarily based on astronomical observations and could change in response to the harvest of the spring season’s crops in the Near East. Currently, the rare date that varies from the vernal equinox formula is dictated by an ecclesiastical calendar.
Although the recent solar eclipse was not to be seen in our region, the upcoming lunar eclipse could be a brief experience of the divine. In the Berkshires, it will be a fleeting partial eclipse on Saturday morning April 4th, minutes before the sun rises in the east and the full moon sets in the west, with Earth in between. According to Fred Espenak, well-known as Mr. Eclipse, the full moon moves through Earth’s shadow two to four times each year, creating eclipses; 35 percent of those are very difficult to detect, 30 percent are partial and 35 percent are total eclipses.
In our hilly terrain, it may be challenging to be at a location with a view to the western horizon before 6:17 a.m., when the eclipse begins. It is a partial eclipse for us because the moon sets at 6:36 a.m., just 19 minutes after Luna enters the deep shadow cast by our planet, known as the umbra. Earlier, at 5:03 a.m., the moon enters the penumbra (Latin paene = almost + umbra=shadow), Earth’s faint shadow that is reputed to escape detection by most onlookers. Sky and Telescope suggests that the penumbral phase may first be visible at 5:35 a.m. Are you curious to find out if you can detect this phase of the eclipse? It might be challenge enough to be up to observe the moon touch Earth’s umbra, the climax here in eastern North America.
Sounds like an invitation to camp out on a west-facing summit! Alternatively, or in addition, one may watch the progress of the total lunar eclipse across the world in real time on Slooh. https://main.slooh.com/event/total-lunar-eclipse-on-april-4-2015/