Mark your calendar for April 15th and set your alarm clock to get you up just before 2:00 a.m. that morning. A spectacular lunar eclipse will occur beginning then and be widely visible from all of North America. (It’s actually the first of two such events this year, the second one happening in October, so you’ll have another chance to experience an eclipse should this one happen to be clouded out!)
This beautiful celestial show begins with the left edge of the full Moon entering the Earth’s dark inner shadow (the “umbra”) at 1:57 a.m. EDT on April 15th and continuing to become ever-more fully immersed in it for the next 69 minutes. Totality itself will occur at 3:06 a.m. and last well over an hour, after which the Moon begins to slowly emerge from the cone of darkness at 4:25 a.m. in reverse order. The right edge of our satellite finally clears the umbra at 5:33 a.m., concluding the show as it continues on in its never-ending journey around the sky.
There are several interesting things to notice as you watch this event unfold. Most obvious are the darkness of the eclipsed Moon and the range of colors displayed, both of which vary from one eclipse to another. These depend on the clarity of the Earth’s atmosphere at the time, which refracts or bends sunlight around and into the umbral shadow. There have actually been eclipses so dark that the Moon remained all-but invisible during totality—and ones so pale that you had to look carefully to see that there was even an eclipse in progress! Among the colors that have been seen are shades of reddish-orange, brown, copper, rose, and even blood-red. Notice, too, that the Earth’s shadow is curved at all phases of the eclipse, as the Moon passes through it. This is direct proof that the Earth itself is round—something recognized by many ancient sky-watchers. And finally, realize that you’re actually seeing our lovely satellite move eastward in its orbit—as it first passes into, through, and then out of the shadow at roughly its own diameter each hour.
While lunar eclipses can certainly be enjoyed with the unaided eye alone (as they have been throughout most of history!), they are best-seen in binoculars. An ideal pair for this would be a 7×50 or 10×50 glass, the first number indicating its magnification and the second the aperture in millimeters. Telescopes themselves, with their relatively narrow fields of view, typically don’t provide enough sky coverage around the Moon to get the full effect of its globe being suspended in space. An exception here, however, is Edmund Scientifics’ amazing Astroscan-Plus wide-field reflecting telescope. Providing a breathtaking 3-degree actual field of view with its 16x eyepiece, it takes in an astounding six full-Moon-diameters of sky—something many have described as looking through the porthole of a spaceship!
— James Mullaney
Former assistant editor at Sky & Telescope magazine & author of nine books on stargazing. His latest, Celebrating the Universe!, is available from HayHouse.com.