Current Release: September 11th, 2007 | Vol. XXIV Iss. 10

Photo courtesy google images

Lunar eclipse for the Americas

By patrick shahayda

mpshahayda@vwc.edu

On Feb. 20, the Hampton Roads area, as well as other choice areas of the globe, were treated to a special sight — a lunar eclipse. Though it was cloudy, if watching hard enough, they were able to discern the moon, which glowed reddish-orange in the night sky. It was a rare sight to behold, when the clouds permitted it.

What is a lunar eclipse? A lunar eclipse occurs when the moon passes into the Earth’s shadow. The

Earth blocks the sun’s rays from reflecting on the moon’s surface. But what causes that reddish glow?

Professor Donald Hanna, who teaches astronomy at VWC, explains: “The red color comes from the basic observation in physics that blue light scatters much better than red light. It’s the same reason sunsets are red.”

The amount of dirt and dust in the upper atmosphere can also determine how well a lunar eclipse shows up. The more particles there are in the upper atmosphere, the harder it is for light to pass through.

Eclipses can occur in two areas of Earth’s shadow, the umbra and the penumbra. In a normal penumbral eclipse, the moon passes through the Earth’s penumbra, which is a zone where the Earth’s shadow and solar rays mix. In a total penumbral eclipse, which is rare, the Moon passes totally in the penumbra and is darkened.

The phenomenon is much the same in the umbra, but it is an area shielded from solar radiation by the Earth’s bulk. It is here where total eclipses of the moon happen.

However, because the Earth has a substantial atmosphere, the moon is always guaranteed to show up during an eclipse. Without an atmosphere, the moon would totally disappear into the cold pitch-black of space.

Unlike solar eclipses, lunar eclipses are harmless on the eyes. You don’t need any special equipment to view them. Lunar eclipses are popular, because their totality last much longer than a total eclipse.

So, around 10 p.m. on the 20th, the moon was reaching the height of its eclipse. Those who caught a glimpse should feel rather lucky, though the weather was not the best for eclipse viewing.

As Hanna explained, “Lunar eclipses are fairly rare. We won’t get another in Tidewater for three more years.”