Lunar Eclipse 10 December 2011
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From Asia to Australia, the Moon will noticeably darken and flare different colours as the Earth blocks the Sun's rays, refracting light through its own atmosphere and colouring the Moon much like the horizon during a sunrise or sunset - a phenomenon known as Rayleigh scattering, the same process that turns the sky blue.
Partial lunar eclipses are reasonably common: there are at least two per year, but total ones are rarer. And they are easy to enjoy - unlike a solar eclipse, which can only be seen from a small part of the world at a time, a lunar eclipse is visible from everywhere on the night side of the Earth, and can last for a few hours, instead of the brief few minutes the Moon obscures the Sun in a solar eclipse.
"Lunar eclipses are nice leisurely events; you can take your time and enjoy them," says Dr Tanya Hill, Astronomer for the Melbourne Planetarium at Scienceworks. Unlike a solar eclipse, you don't need any protective equipment or even a telescope. You can take your time, and view it from anywhere - provided it is during the night.
This particular eclipse will have 51 minutes of totality - that is, almost an hour when the Earth is completely eclipsing the Moon, and the whole eclipse from start to finish will take about 3.5 hours.
And what is remarkable, Tanya says, is that as the Earth's shadow moves across the Moon, "you are seeing how we are moving through space." It's easy to forget we are hurtling along our orbit at 30km/s, or 108,000km/h.
While it is difficult to forecast, astronomers are predicting a blue pinch to the Moon's changing colour as the Earth crosses the alignment.
"The shadow will be very dark," Tanya says, "it could redden, and could also have a bluish turquoise hue to it too." But it all depends on the Earth's atmosphere.
Make sure your eyes are peeled for the eclipse, beginning its partial eclipse at 11:46pm in Melbourne, Sydney and Canberra (AEDT) on Saturday. The total eclipse begins at 1:06am and lasts for nearly an hour.
09 Dec 2011 Thanks for informing readers about the total Lunar eclipse and the times to view it in different cities. The skynotes link is also very helpful.
10 Dec 2011 Thanks for the info but I have one small beef! - when the Earth's shadow moves across the Moon we aren't really seeing the Earth's orbital speed of 30km/sec - if we were it would cross the Moon in about 14 seconds. The Moon accompanies the Earth in its orbit about the Sun so has the same mean Solar orbital speed as the Earth. What we are seeing is mostly the orbital velocity of the Moon about the Earth of about 1km/sec (there's a minor parallax correction due to the movement of the two bodies about the Sun during the eclipse).
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