Astronomy Professor Ed Murphy Previews Wednesday's Lunar Eclipse

February 18, 2008 — The eastern United States will be treated to a total eclipse of the moon on Wednesday, Feb. 20. A lunar eclipse occurs when the moon passes into Earth's shadow. Within the space of a few hours, the bright full moon will disappear, cross Earth's shadow, and then reappear.

The moon will begin to enter the darkest part of Earth's shadow at 8:43 p.m. EST. It will take 78 minutes for the moon to go through its disappearing act. The moon will be completely inside the Earth's shadow (total eclipse) from 10:01 p.m. to 10:51 p.m., with the deepest part of the eclipse at 10:26 p.m. From 10:26 p.m. to 12:09 a.m., the moon will gradually reappear.

During most total lunar eclipses, the moon does not completely disappear from view. Light is refracted, or bent, by Earth's atmosphere and can still dimly illuminate the moon. Since this is the combined light from all the world's sunsets and sunrises, the moon takes on a distinct coppery red color.

To see the eclipse, head outside around 8:30 p.m. on Wednesday evening. Watch as the moon slowly slips into Earth's shadow from 8:43 p.m. to 10:01 p.m. Telescopes or binoculars are not needed. A lunar eclipse is perfectly safe to view with the naked eye.

Contrary to popular belief, Columbus was not the first person to prove the world was round. As the moon slips into the shadow of the Earth, you should note that Earth's shadow is clearly curved and larger than the moon. These observations were used by the great Greek philosopher Aristotle to prove that Earth was round, circa 350 B.C. He noted that only a sphere always produces a curved shadow, and that the size of the shadow indicated Earth was larger than the moon.

In case you are planning to hold out for the next total lunar eclipse, be aware that there will not be another total lunar eclipse until Dec. 21, 2010!

By Edward Murphy, associate professor of astronomy and manager of the Department of Astronomy’s education and public outreach program