America will get best view of tonight's lunar eclipse show

Published: Thursday, January 20, 2000



The sun, as always, maintains its station. The Earth, on its constant orbit around the brightly burning star, swings into position. And the moon slides into place behind the Earth.

Conditions are right for a lunar eclipse when the sun, Earth and moon align in a straight row. The Earth, situated between the sun and moon, prevents sunlight from reaching the orbiting moon as it moves around the Earth's night side.

As the Earth orbits the sun, it casts a cone-shaped shadow that extends 850,000 miles into space. A lunar eclipse occurs when a full moon passes through this shadow, about 239,000 miles from the Earth.

The Earth's dark shadow is called the umbra. Its diameter measures 5,700 miles, more than twice the size of the moon. A trip by the entire moon through the umbra causes a total eclipse. If the moon only grazes the umbra, then you'll see just a partial eclipse.

A lighter shaded zone on the Earth's shadow surrounding the umbra is called the penumbra. On occasion, the moon passes through part of the penumbra but not the umbra. When this happens, a pale, fuzzy shadow will cover part of the moon.

Why don't lunar eclipses occur every month? The answer is fairly simple.

Usually the sun, moon and Earth don't arrange themselves in a straight line. Because the moon's orbit is tilted about 5 degrees in relationship to the Earth's orbit around the sun, the moon usually passes above or below the imaginary line that connects sun and Earth. Because of this, the moon usually does not pass through the Earth's shadow.

According to Susan Holtz, astronomy teacher at Texas Tech, the moon in its deepest eclipse will appear an orange-red color while the earth is blocking the direct light of the sun.

However, a ring of atmosphere on the earth will bend and scatter the light of the sun that is traveling toward the moon.

"This is the light coming from all the sun-ups and sunsets that are occurring on the earth," she said.

"Sun-ups and sunsets are basically red, so there is a scattering of red and orange light into where the moon is, and that is going to reflect to earth.

"So, at the deepest part of the eclipse, the moon is going to be an orange-red color all the beautiful colors that are coming from all the sun-ups and sunsets all over the earth."

Holtz said there is no danger of eye damage from looking at the moon, and that not even a telescope is needed.

"You don't need any special equipment except maybe some strong coffee to stay awake, and a heavy coat if it's cold."

The moon will return to its full-moon status after 12:25 a.m.


Through the ages, superstitions and myths have fed fears about lunar eclipses. Different cultures have responded in unique and sometimes deadly ways to cope with the disappearance of the moon.

(A-J feature writer Ray Westbrook contributed to this report.)

