If you’re anywhere in 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 put an end to the show.
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. The partial stage of the eclipse begins more than an hour earlier, at 4:45 a.m. PST.
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.
“That red light on the Moon during a lunar eclipse comes from all the sunrises and sunsets around the Earth at the time,” explains Sky & Telescope 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 illuminate the lunar landscape around you.”
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 a small telescope.
Future 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.
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For skywatching information and astronomy news, visit SkyandTelescope.com or pick up Sky & Telescope, the essential magazine of astronomy since 1941. With subscribers in more than 100 nations, and having recently published its 70th anniversary issue, Sky & Telescope is the essential magazine of astronomy. Sky Publishing (a New Track Media company) was founded in 1941 by Charles A. Federer, Jr. and Helen Spence Federer, the original editors of Sky & Telescope magazine. In addition to Sky & Telescope and SkyandTelescope.com, the company publishes three annuals (Popular Astronomy, SkyWatch, and Beautiful Universe) as well as markets books, star atlases, posters, prints, globes, and other fine astronomy products.
New Track Media was formed in 2006 by Stephen J. Kent and Boston Ventures for the purpose of building up a premier consumer-enthusiast publishing platform in a range of special interest subject areas. In its first year, the company completed three acquisitions: Sky Publishing, the leading publisher of astronomy periodicals and books, headquartered in Cambridge, Mass.; Fons & Porter’s Love of Quilting, based in Winterset, Iowa; and American Woodworker, which is located in Eagan, Minnesota, and the Creative Crafts Group. New Track operates from offices in Cincinnati, Ohio, and Cambridge, Massachusetts.
