The action begins at 3:16 AM Pacific Daylight Time on the morning of April 4th when the edge of the Moon first enters the amber core of Earth’s shadow.
For the next hour and 45 minutes, Earth’s shadow will move across the lunar disk, ultimately swallowing the entire Moon at 4:58 AM PDT.
East of the Mississippi River, the eclipse will be interrupted by sunrise. People can see only a partial eclipse. West of the Mississippi River, people can see the whole thing, including totality.
“Totality” is when the Moon is fully inside Earth’s shadow. Some total eclipses last for more than an hour. In this case, however, totality spans just 4 minutes and 43 seconds—a result of the fact that the Moon is skimming the outskirts of Earth’s shadow rather than passing centrally through it.
A quick trip to the Moon provides the answer: Imagine yourself standing on a dusty lunar plain looking up at the sky. Overhead hangs Earth, nightside down, completely hiding the sun behind it. The eclipse is underway.
The total eclipse of April 4, 2015, is the third of four total lunar eclipses separated by approximately 6 months, a phenomenon astronomers call a “tetrad.” Such a closely-spaced succession of eclipses is a fairly rare occurrence. The complete list of dates is April 15th, 2014; Oct. 8th, 2014; April 4th, 2015; and Sept. 28th, 2015.
By Stephen Pate, NJN Network