Fifteen days after it totally eclipsed the Sun, the Full Moon will itself become totally eclipsed early on Saturday morning, April 4th. Both events, of course, are related. A solar eclipse can occur only when the Moon is at a node in its orbit. (The nodes are the two points where the Moon’s path in the sky crosses the Sun’s path, the ecliptic). During the solar eclipse the Moon was crossing the ecliptic from north to south. A half orbit later it will cross the opposite node from south to north, encountering the Earth’s shadow. All this is a fine example of how an eclipse season works.
This eclipse will be visible in varying extent across North America. The farther west one goes, the better the view. The Moon will be approaching its setting as the eclipse begins. From the Canadian Maritimes, the best one might hope to see is a faint bit darkness – call it a “soiled” or “smudgy” appearance on the left rim of the Moon as it drops below the western horizon – evidence of the Earth’s outer shadow, the penumbra.
When the Moon makes first contact with the darker umbral shadow (6:15 a.m. EDT; 3:15 a.m. PDT), it will appear as if a bite were taken out of the Moon’s disk. East of a line running from central Minnesota to central Louisiana, the Moon will set before totality. From Boston, roughly 10 percent of the Moon’s diameter will be eclipsed when it sets at 6:26 a.m. EDT. New York will see about 23 percent coverage at moonset (6:39 a.m. EDT). Farther west, the progression of the Moon into the umbra will be much greater: Chicago, 76 percent (6:34 a.m. CDT) and Memphis, 90 percent (6:48 a.m. CDT).
This will be an extremely short total lunar eclipse. According to NASA astronomer, Fred Espenak, totality begins at 6:57:54 a.m. CDT (3:57:54 a.m. PDT) and will last just 4 minutes 43 seconds. This is because the Moon just barely becomes entirely immersed within the umbra. In fact, at mid-eclipse, the Moon’s northern limb is tucked within less than 2 miles of the outermost edge of the umbra!
After totality, the western half of North America will see the Moon gradually emerge from the umbra. For most, moonset will intervene before the Moon completely exits the shadow, although along the West Coast the Moon’s last contact with the umbra (on its right/western rim) can be glimpsed before local moonset at 6:44 a.m. PDT.
The next total lunar eclipse will occur on Sunday night, September 27 and will be visible across all of North America. And that will also be the night of this year’s “Super” Full Moon. Mark your calendars!