Sunday, 11 December 2011

eclipse

Going, going....

I’ve seen quite a few eclipses of the Moon over the years, but last night the sky was completely clear, and for the first I was able to watch one from the comfort of my own home with a bottle of red wine for company. Mind you, ‘comfort’ may not be the most appropriate word to use, because as Paula and I sat on our balcony watching the Earth’s shadow creep slowly across the lunar disc, a strong and very cold wind was blowing from the north.

I couldn’t help but recall the two coldest nights I’ve had to endure during my lifetime. The first was in 1968: I’d just arrived in Libya, and I’d heard that it got very cold during the night in the desert, so I’d brought a thick sweater with me.

“You’ll need a jacket,” said my colleague.

So I bought a suitable jacket at the local oilfield supplies store. On my first night in the desert, I made sure to wear both the sweater and my newly acquired jacket as I worked through the hours of darkness. I’ve no idea of the actual temperature, but I couldn’t wait for that ‘busy old foole’ to rise the next morning and thaw me out.

My second cold night experience was in Glen Affric, in the Western Highlands of Scotland, in 1973. Because of the snow conditions, I’d been unable to reach my intended destination, so I decided to spend the night in a bothy, a makeshift shelter of a kind that is found all over the Scottish Highlands. I had with me a high-quality down sleeping bag and a polar-quality down jacket, which I decided to wear to be on the safe side. I shivered all night.

I also recalled a lunar eclipse that I’d witnessed, off and on, in 1978. Actually, it was more off than on, because I was driving a taxi at the time, so I did have to pay attention to where I was going. However, during the eclipse I amused myself by asking each passenger I picked up whether they’d noticed anything unusual.

“You do realize that we’re in the middle of an eclipse of the Moon,” I said, as each passenger answered in the negative.

I assume that the night sky does not hold the same mystery for modern humans as it did for our remote ancestors. Even my wife, who is usually quite inquisitive, tends not to look up.

“Notice anything unusual?” I asked her a couple of years ago on the first night of a trip down under to stay with an Australian friend.

No, she hadn’t. Of course, I had the advantage of spending almost the whole of 1970 in the Australian outback, so I already knew about the extreme blackness of the night sky. And there is more to see in the southern hemisphere too, notably the Magellanic clouds, seen by Ferdinand Magellan, as the name implies, during his circumnavigation of the world in 1519–21 but known to earlier astronomers in the southern part of the Arabian peninsula.

These are nearby galaxies, although ‘nearby’ is a relative term here. The smaller of the two is 160,000 light years away and the larger 200,000 light years. They are also much smaller than our own Milky Way, which is unmistakeable against such a vividly black background.

But back to last night: it took 81 minutes from the time the Moon entered the Earth’s shadow until it was completely obscured; the total eclipse lasted 52 minutes, and a further 82 minutes elapsed before the Moon emerged from the shadow. Oddly, when the eclipse started, the Moon seemed so bright that it was impossible to focus on it (see first image above), and with the naked eye the boundary between the still-lit and the darkened parts of the Moon was anything but clear-cut. During the total phase, the Moon didn’t disappear completely but appeared a dull, reddish brown disc, illuminated by the small amount of light that was being diffracted by the Earth’s atmosphere.

The Hong Kong Observatory’s website tells me that there will be an annular eclipse of the Sun on 21st May next year. Now that’s something I have never seen.

...gone (almost).

5 comments:

  1. How exciting, Dennis! Wish I had been there with you. As far as I know the eclipse didn't happen here in NY, but we did have a perfect clear sky last night and a stunning full moon. I'm an avid sky watcher and am constantly looking up, both night and day. What I see never fails to delight and astonish me. Sometimes I credit my total ignorance of science to that fact, but obviously that's not the case with you.

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  2. I saw it from where I am in Arizona.
    It was beyond words.

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  3. “What I see never fails to delight and astonish me.”

    NP, that shouldn’t be an excuse, although perhaps it’s my formal science background that makes me want to find out why something happens or how something works once I’ve been delighted and/or astonished.

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  4. never in my life i witnessed any such natural occurences, even though i did experience lots of cold nights (the "cold" here is a relative term, even thought it shouldn't be count by 'light-years').
    thanks for sharing! i do admire your life experience. :-)

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