Total moon eclipse to darken night sky Monday

By Roy Gephart, StargazingApril 12, 2014 

"Those who contemplate the beauty of the earth find reserves of strength that will endure as long as life exists." -- Rachel Carson

Each spring day greets us with a few more minutes of light, tulips reaching skyward and morel mushrooms awakening to mountain sunshine.

On quiet walks, we hear the low-pitched calls of Sandhill Cranes flying high overhead -- venturing northward to nesting grounds in Canada and Siberia. Even my fishing tackle is nudging me toward the rush of snow-melt streams.

Tomorrow night, spring unfurls another natural beauty -- the first total eclipse of the moon seen across most of North American since 2011.

Amazingly, three additional lunar eclipses will be visible during the next 18 months.

A total lunar eclipse takes place when the moon passes through the center of the Earth's shadow during its orbit around our planet. This eclipse can only occur during full moon and when the sun, Earth and moon align in a straight row.

We don't experience an eclipse every full moon because it normally passes above or below the shadow.

The first hint of Monday night's eclipse begins at 10:58 p.m., when the Earth's dark, curved shadow begins nipping away at the eastern (left) edge of the moon.

Why the left side? The moon moves that direction as it circles the Earth once every 29 days.

With each passing minute, the moon buries itself deeper inside the shadow.

The moon lies totally inside the shadow by a few minutes after midnight. This marks the beginning of totality -- the most colorful phase of the eclipse.

Totality lasts for almost 90 minutes.

At 1:25 a.m. Tuesday morning, the moon's left side will begin to brighten as it edges out of the shadow.

By 2:33 a.m., the full and partial phases of the eclipse will have ended. A luminous full moon once again will shine a bright charcoal gray.

During the eclipse's total phase, no sunlight falls directly upon the moon's landscape because the Earth blocks the sun like a huge cosmic umbrella.

The only illumination comes from the coppery colors of a continuous ring of sunrises and sunsets bent into the shadow by the thin rim of atmosphere encircling the Earth.

During totality, the moon might turn light orange to almost black. We'll have to wait and see.

Color depends on the amount of cloudiness and dust in the Earth's atmosphere. The cleaner the atmosphere, the brighter the eclipse. The more opaque the atmosphere, the darker the eclipse. Like people, each eclipse is different.

In 1982, I watched a lunar eclipse from atop Rattlesnake Mountain. Rather than seeing the eclipsed moon turn orange, large dark blotches drifted across a deeply red-tinted lunar landscape. This odd phenomenon was caused by dust ejected into the Earth's atmosphere earlier that year from an eruption of the El Chichon volcano in Mexico.

The best way to view Monday's eclipse is with your unaided eyes. A pair of binocular will add to your viewing enjoyment.

-- Roy Gephart is a retired environmental scientist and an avid amateur astronomer. He can be reached at roygephart@yahoo.com.

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