June 14, 2011 at 10:46 PM ET
North America is totally out of the picture for Wednesday's unusually long total lunar eclipse — unless, that is, you're tuning the show in over the Web. If you click on the right website, the view could be totally cool.
Unlike total solar eclipses, which can be seen only from a narrow track of territory, lunar eclipses are visible from half of the globe at once. It's just a function of bad luck (and orbital mechanics) that North America is on the wrong side of the world throughout the entire five and a half hours of Wednesday's eclipse — including 100 minutes of totality, from 3:22 p.m. to 5:02 p.m. ET. The last time the total phase of a lunar eclipse lasted that long was 11 years ago.
Lunar eclipses may not be as spectacular as the "black sun" spectacle of the solar kind, but they're well worth watching nevertheless. Such events occur during the time of the full moon, when the moon's orbit takes it smack-dab through Earth's shadow. It's not a common occurrence, but it's not exactly rare, either. There are generally one or two lunar eclipses of some sort every year.
The beginning of the eclipse is barely perceptible, but minute by minute, more and more of the moon's disk darkens until the onset of totality. When the moon is completely within the shadow, it often has a rusty/red/orange/brown glow to it. That's the glow of a world's worth of sunsets — or if you want to put it less poetically, the reddish wavelengths of sunlight that are refracted around Earth's disk by the atmosphere. This archived story explains the "red moon" effect in depth.
Wednesday's lunar eclipse could be exceptional for a couple of reasons, as University of Colorado atmospheric scientist Richard Keen explained to SpaceWeather.com:
"The moon will pass deep into Earth's shadow during totality, actually passing over the center of the shadow at mid-eclipse. As such, it should be a fairly dark eclipse. Furthermore, it appears that last week's eruption of the volcano in Chile may have placed some sulfur dioxide into the stratosphere. The ash and sulfur plume is extensive and dense, with ash reported at least as high as 13.7 km. Particles in the southern stratosphere could cause a darkening of the southern part of the moon during totality."
Here are the turning points for Wednesday's eclipse:
All this is what North Americans could be missing, unless you check out the Web. Here's a listing of scheduled eclipse webcasts. Some of these links might be duds, due to cloudy weather, technical glitches or plug-in requirements. But let's hope that at least a few will serve up a good show:
This time around, the only way to experience the eclipse from North America is over the Web, or through the pictures that will no doubt be posted to SpaceWeather.com and other websites. If you've got a great picture of Wednesday's eclipse, feel free to drop me a line.
And if you happen to live around the Pacific Rim, there's another show coming your way in December. The next lunar eclipse is due to occur on Dec. 10, with prime viewing available from Australia and most of Asia. Alaska and the Pacific Northwest will also get in on the total phase — which means that if the skies are clear up here in Seattle, we're in for a holiday treat. For the complete lineup of lunar and solar eclipses, going all the way to the year 3000, check out the NASA Eclipse Web Site.
Update for 3:30 p.m. ET June 15: You can watch the eclipse on several of the sites above, but for English-speakers, it's hard to beat the Slooh coverage of the event, which includes continuous audio commentary. Later in the day we'll have a speeded-up video of the event so that you can watch the eclipse's complete total phase in a minute. Google also has taken note of the lunar eclipse and is making it today's "doodle" for its search page. Learn more about the Google doodle from the company's blog.
More about eclipses:
Tip o' the Log to Astronomers Without Borders.
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