A treat for early risers

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by Tanya
Publish date
16 June 2011
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A rare event happened this morning... when my one-year-old started calling out for Mummy just after 4am, the usual dread of having to face another cold and early start was gone, replaced by the thrill that my little guy was just the perfect astronomer!

This morning we were treated to a total lunar eclipse and it began with a beautiful starry, but certainly cold, morning sky. Just before 4.30am a small chunk was seen to be missing from the top right of the Moon. The first sign that the Earth's shadow had found its target.

Lunar Eclipse The Earth's shadow hit its target.
Image: Tanya Hill
Source: Museum Victoria
 

Lunar eclipses occur on those rare occasions when the Sun, Earth and Moon are in perfect alignment. They only ever happen at the time of Full Moon, when the Sun and Moon are on opposite sides of the Earth. Most of the time the Earth's shadow misses the Moon, falling either above or below it, but this morning it was right on track.

By 5am, the Earth's shadow was covering more than half the Moon and a reddish glow was already beginning to appear. The stars was twinkling perfectly, with one of my favourite constellations, that of Scorpius, sitting directly to the left of the Moon, and the centre of the Milky Way right above it. Totality officially began at 5.23am and the Moon was certainly an eerie red colour.

Where does that red come from? Well the only way sunlight can now reach the Moon is by passing through the Earth's atmosphere. That light gets bent and scattered, so only the reddest light can make it through. Particles in our atmosphere, like the volcanic ash that's been annoying so many air travellers these last few days, added to the scattering effect, making the eclipse redder and darker than the last few that I remember.

For those who love statistics, totality was due to last 100 minutes, making it the longest lunar eclipse since 2000, which clocked in at 106 minutes. A rough rule of thumb is that totality generally takes around one hour, but a couple of times each decade we get a good one lasting 90 minutes or more. This was one of those.

Except for those pesky clouds that rolled in just after 6am, blocking the view for those who got up at their usual time. They were obviously in need of my own precious little alarm clock.

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Jareen 16 June, 2011 10:27
Thanks for this informative blog post Tanya. I too was up super early to catch the eclipse - it certainly was spectacular. Nice reminder on how big and beautiful the universe is.
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