Watch the Dawn Eclipse of the Moon, Dec. 10, 2011

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Taking a break from Game 4 of the World Series on October 27, 2004, Sky & Telescope editor in chief Rick Fienberg snapped this view of that evening’s total eclipse of the Moon. Click on the image for a larger version. Sky & Telescope photo by Richard Tresch Fienberg

If you’re anywhere in central or western North America, mark your calendar to get up before dawn this Saturday, December 10, 2011. That morning the full Moon goes through its last total eclipse until 2014.

The farther west you are in the U.S. or Canada, the better you’ll be set up for the show. If you’re in the Pacific time zone you can watch the Moon slip into Earth’s shadow completely, while the Moon is sinking low in the west-northwestern sky and dawn is brightening. In the Pacific Northwest and westernmost Canada, you can even see the Moon start to emerge from our planet’s shadow after the total eclipse is over — until moonset and sunrise end the show.

Family Reading Night at St. Lawrence O'Toole
How much of the dawn lunar eclipse will be visible for you? For your location, this map tells what stage the eclipse will have progressed to by the time the Moon sets below your west-northwestern horizon.

The Sun rises right around the same time an eclipsed Moon sets. This means the sky will have been growing brighter and brighter up to then. (Dawn begins about an hour and a half before sunrise). (Sky & Telescope)

From roughly Arizona to the Dakotas, the Moon sets while it’s still totally eclipsed — though horizon obstructions and the brightening dawn may end your view somewhat before then.

In the Central time zone the Moon sets while still only partially eclipsed, before the total stage even begins. And those farther east miss out completely.

Skywatchers in Hawaii, Australia, and East Asia have it better. Seen from there, the whole eclipse happens high in a dark sky from start to finish. For Europe and Africa, the eclipsed Moon will be lower in the east during or after twilight on the evening of the 10th.

Unlike an eclipse of the Sun, an eclipse of the Moon is visible to everyone on the entire Moon-facing side of the world at once. “We’re all looking at this together,” says Sky & Telescope senior editor Alan MacRobert.

The eclipse will be total from 6:05 to 6:57 a.m. Pacific Standard Time, as shown in the table below. The partial stage of the eclipse begins more than an hour earlier.

When the Moon is totally eclipsed, it glows eerily orange, red, or dark bloody brown. Although the Moon is completely inside Earth’s shadow, it’s still dimly lit by sunlight that skims the edge of Earth and is refracted (bent) into Earth’s shadow by the atmosphere.

Family Reading Night at St. Lawrence O'Toole
Aligning his camera on the same star for nine successive exposures, Sky & Telescope contributing photographer Akira Fujii captured this record of the Moon’s progress dead center through the Earth’s shadow in July 2000. This image is available as a publication-quality JPEG (1.5 megabytes). Sky & Telescope / Akira Fujii

“That red light on the Moon during a lunar eclipse comes from all the sunrises and sunsets around the Earth at the time,” explains S&T editor in chief Robert Naeye. “If you were an astronaut standing on the Moon and looking up, the whole picture would be clear. The Sun would be covered up by a dark Earth that was ringed all around with a thin, brilliant band of sunset- and sunrise-colored light, bright enough to dimly light the lunar landscape around you.”

December 10th’s Total Lunar Eclipse
Partial eclipse begins 12:45 6:45 a.m. 5:45 a.m. 4:45 a.m.
Total eclipse begins 14:05 7:05 a.m. 6:05 a.m.
Mid-eclipse 14:32 7:32 a.m. 6:32 a.m.
Total eclipse ends 14:57 7:57 a.m. 6:57 a.m.
Partial eclipse ends 16:18

During this eclipse, the Moon barely skims inside the southern side of Earth’s shadow. So we can expect the Moon’s southern rim to remain brighter than the rest — creating a lovely 3-D effect and drama for photographers. To get a good image scale, use a long telephoto lens or even a small telescope.

Next eclipses

The next eclipse of the Moon will be only partial, happening before and during dawn on June 4, 2012. It will be visible from most of North America except the Northeast.

The next total lunar eclipse doesn’t come until the night of April 14-15, 2014. But then the Moon will be positioned high in a dark sky for viewers all across the Americas.