The last eclipse of 2011, a total lunar eclipse, will occur early Saturday morning (Dec. 10). Although best placed for observers in Australia and eastern Asia, part of the eclipse will be visible from the west coast of Canada and the United States.
A total lunar eclipse occurs when the Earth passes between the sun and the moon, casting the moon in shadow. The last such eclipse took place in June 2011.
For observers in North America, this eclipse will happen just before dawn Saturday morning. To see it, stay up late Friday night or get up early Saturday morning. Alaska will see all of the eclipse, British Columbia most of it, the views will decrease as you move south and east from there.
"From roughly Arizona to the Dakotas, the moon sets while it's still totally eclipsed," writes Sky & Telescope magazine. "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."
The eclipse will begin at 3:33 a.m. PST, when the faint outer penumbral shadow touches the moon. The eclipse will be obvious by 4:45 a.m., when the dark umbral shadow begins its trip across the moon's face. The total eclipse phase will start at 6:06 a.m. and last for 51 minutes.
In Sydney, the eclipse will begin at 10:33 p.m. Saturday evening and last most of the night. Totality is from 1:06 a.m. until 1:57 a.m. local time.
It's difficult to predict in advance how dark any particular lunar eclipse will be. It’s extremely rare for the moon to disappear completely because some sunlight always leaks past the Earth through the twilight zones.
Because this light is coming from countless sunsets on Earth, it is usually tinged reddish in color. If cloud cover on Earth is dense, very little light gets through, and we get a very dark eclipse.
Because this eclipse will be low in the western sky in North America and low in the south in Australia, there should be plenty of photo opportunities.
If you take a photo or video of the eclipse that you'd like to share with SPACE.com for a possible story or gallery, please email Tariq Malik at email@example.com or Clara Moskowitz at firstname.lastname@example.org.
This article was provided to SPACE.com by Starry Night Education, the leader in space science curriculum solutions. Follow Starry Night on Twitter @StarryNightEdu.