Wednesday, August 29, 2007

Lunar colour sequence


Last night (28 Aug) was a total lunar eclipse. We were lucky in NZ because it started in the evening so we had a good view.

So far as lunar eclipses go it was pretty typical, most adults would have seen one or two in their lives. It was under constant threat by cloud, and at times not visible, but it was quite a spectacle regardless.

The photo is from the last stages of the moon entering the Umbra, or darkest part of Earth's shadow.

Being stuck on a phone conference at the time was no obstacle, I sat outside and set my laptop on a garden table and did my conference and demo from the backyard.

However what makes this eclipse noteworthy over others is the timing...

Last month (July 2007) we had a "Blue moon". A Blue moon can have several definitions, but one of the more accepted ones is where there are two full moons in the same calendar month.

Given that the lunar cycle is only just shorter than a calendar month, it can happen. Just not very often. Hence "Once in a Blue Moon".

So in this case, we have a Blue moon followed by a Red moon.

How often will that happen in your lifetime?

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