Saturday, December 10, 2011

Total Lunar Eclipse This Weekend—Last One Until 2014

Total Lunar Eclipse This Weekend—Last One Until 2014
A composite photograph shows the stages of a total lunar eclipse.

A composite picture of the full moon before, during, and after a total lunar eclipse.

Photograph courtesy Akira Fujii, Sky & Telescope

Andrew Fazekas

for National Geographic News

Published December 9, 2011

This weekend sky-watchers across most of the globe will have the chance to watch at least some of the last total lunar eclipse until 2014.

(Pictures: Lunar Eclipse "Preview"—What You'll See Saturday.)

The entire lunar eclipse will be visible in East Asia, Australia, and the far western portion of North America that includes Alaska and Canada's Yukon and Northwest Territories. The spectacle will last nearly three and a half hours, starting on Saturday at 4:45 a.m. Pacific Time.

Totality—when the full moon will be completely blocked from direct sunlight—will start at 6:05 a.m. PT and last until 6:57 a.m. PT.

Part of the eclipse will be visible in Europe and Africa at moonrise, in the evening, said Raminder Singh Samra, an astronomer at the H.R. MacMillan Space Centre in Vancouver, Canada.

"Meanwhile, observers across the Pacific region of North America will get to see the sky show low in the western horizon at moonset, in the early morning," he said.

Watch a live video feed of the total lunar eclipse from the Slooh SpaceCamera. Live broadcast starts at 5:00 a.m. PT on Saturday.

Painting the Full Moon Red

Lunar eclipses can occur only when the full moon, Earth, and the sun are aligned so that the moon crosses through Earth's shadow.

Due to the moon's tilted orbit around Earth, lunar eclipses happen only a few times a year, Samra said. The eclipse can be full or partial, depending on how much of the lunar disk falls in our planet's shadow.

(Watch a moon facts video.)

Rather than going completely dark, the moon takes on a deep reddish hue during a total lunar eclipse.

"As the entire moon passes through the Earth's shadow cast by the sun in space, sunlight scattering off our planet's dusty atmosphere and subsequently reflecting off the surface of the moon will make it appear to change color," Samra said.

Expect to see the lunar disk go from dark grey during the partial phase to reddish-orange during totality, he said.

(See "Lunar Eclipse Pictures: When the Moon Goes Red.")

Partial Eclipses on the Horizon

After Saturday's eclipse, sky-watchers are in for a dry spell—the cosmic lineup needed for a total lunar eclipse won't occur again until April 14, 2014.

(Take a moon myths and mysteries quiz.)

But the next partial lunar eclipse happens on June 4, 2012, when a chunk of the moon will appear to be gobbled up by Earth's shadow.

"The next few lunar eclipses that will occur will only be partial ones," Samra said, "so this will be our last chance to enjoy a total eclipse in quite some time."

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