The last eclipse of 2011 is a total lunar eclipse on December 10 visible from Vancouver, Seattle, California, Oregon, Canada, Calgary. There won’t be another total lunar eclipse for three years. Viewers in the western half of the United States will have the best views Saturday well before dawn. The farther west the better.
Google Doodle (as the tech giant likes to call the logo on its search engine site) will mimic the eclipse with photos of the actual event itself. A click and a push of the slider under the doodle moves the images from a white moon to red and back to white again, replicating the Earth’s shadow passing by. The lunar eclipse will also be on YouTube.
Weather permitting, Seattle could get a rare eyeful in the wee hours of Saturday morning. The total eclipse will begin at 6:06 a.m. PST and last for 61 minutes, but Seattle Total Lunar Eclipse watchers will get their best view of the eclipse’s early stages around 5 a.m. The best views will be from the top of a hill.
The scene from the Pacific — Australia and parts of Asia — will be prime. The action will be unfolding there Saturday night, local time. In order to observe the selenelion, you should make sure that both your east-southeast and west-northwest horizons are free of any tall obstructions that might block your views of the setting moon or rising sun. Depending on the clarity of your sky, you might actually lose sight of the moon about 10 or 15 minutes before sunrise thanks to the brightening morning twilight and the moon sinking into any horizon haze (atmospheric “schmutz”). This holds only for the uneclipsed portion of the moon. Indeed, if the moon is totally eclipsed at moonset, you will probably have to scan the western horizon as the twilight increases in order to detect the moon, which will perhaps resemble a dim and eerily illuminated softball.
Western Canada, including Vancouver, is the place to be for Saturday morning lunar eclipse. Environment Canada is forecasting just a few clouds overnight for the Vancouver region.
The Moon’s orbital trajectory takes it through the southern half of Earth’s umbral shadow. Although the eclipse is not central, the total phase still lasts 51 minutes. The Moon’s path through Earth’s shadows as well as a map illustrating worldwide visibility of the event are shown in Figure 6. The timings of the major eclipse phases are listed below.
Penumbral Eclipse Begins: 11:33:32 UT
Partial Eclipse Begins: 12:45:42 UT
Total Eclipse Begins: 14:06:16 UT
Greatest Eclipse: 14:31:49 UT
Total Eclipse Ends: 14:57:24 UT
Partial Eclipse Ends: 16:17:58 UT
Penumbral Eclipse Ends: 17:30:00 UT
At the instant of greatest eclipse (14:32 UT) the Moon lies at the zenith in the Pacific Ocean near Guam and the Northern Mariana Islands. The umbral eclipse magnitude peaks at 1.1061 as the Moon’s centre passes 21.4 arc-minutes south of the shadow axis. The Moon’s northern limb is then 6.4 arc-minutes south of the shadows axis and 33.3 arc-minutes from the umbra’s edge. In contrast, the Moon’s southern limb lays 36.5 arc-minutes from the shadow centre and 3.2 arc-minutes from the southern edge of the umbra. Thus, the northern half of the Moon will appear much darker than the southern half because it lies deeper in the umbra.
Since the Moon samples a large range of umbral depths during totality, its appearance will change dramatically with time. It is difficult to predict the brightness distribution in the umbra, so observers are encouraged to estimate the Danjon value at different times during totality (see Danjon Scale of Lunar Eclipse Brightness). Note that it may also be necessary to assign different Danjon values to different portions of the Moon (i.e., north vs. south).
During totality, the winter constellations are well placed for viewing so a number of bright stars can be used for magnitude comparisons. Aldebaran (mv = +0.87) is 9° to the southwest of the eclipsed Moon, while Betelgeuse (mv = +0.45) is 19° to the southeast, Pollux (mv = +1.16) is 37° east, and Capella (mv = +0.08) is 24° north.
The entire event is visible from Asia and Australia. For North Americans, the eclipse is in progress as the Moon sets with western observers favored by a larger fraction of the eclipse before moonset. Observers throughout Europe and Africa will miss the early eclipse phases because they occur before moonrise. None of the eclipse can be seen from South America or Antarctica.
So, enjoy the total lunar eclipse on December 10 from Vancouver, Seattle, California, Oregon, Canada, Calgary..