Philatelly

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First, apologies to Google for using this image. If I’m in trouble I will delete it.

There was a question of Facebook which had an image of a mountainous island and a palm tree. Below it, it said ST Lucia W. I.

I had to think, I jokingly said Women’s Institute. I had an inkling of what I thought WI meant, but didn’t want to say….

Someone said West Indies, which makes perfect sense. But my guess was Windward Isles. So I Googled it…

I don’t know why I  knew it. But I think it was because I collected stamps when I was a child. It’s amazing what memories you can retain over decades. NoytyaCCCCP, Magyar Posta, are a couple of names if places I also remember (may not be the correct spelling).

I wanted to do Geography when I was at school. I was persuaded to do a language instead which I failed abysmally. Maybe I should have done it.

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How to tell the earth is a sphere…

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So how can you tell the Earth is a sphere? The ancient Greeks worked it out ( I don’t remember the name of the person who did).

The experiment was to put a stick in the sand at or near the equator, so it would have a tiny shadow directly underneath the it at mid day as the Sun was directly overhead.

If you place a stick upright, at 90° to the Eaths surface either North or South of the equator, the stick casts a shadow at mid day. (Look at the hands of a clock the hands move round in the same way). Say the equator is 3pm and the Sun is overhead, you would get no shadow, then as you go further away from the stick at the equator you get increasing angles (see diagram). Eventually at the poles the shadows would be at their longest.

So how can you tell its a sphere? The angles add up. You can calculate the curvature of the planet from these simple experiments. The ancient Greeks got very close to calculating the circumference of the Earth. Their calculations were only a small percentage out on their measurement.

 

Sunrise, Sunset.

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I’ve looked at maps all my life, but never noticed that it gets dark earlier in the South East in summer than in the North West. Of course I know the Earth is tipped at an angle, something like 22° and I know that at the equator day and night are about the same length and that sunrise and sunset are about 6pm. But I hadn’t noticed the angle that the terminator of day and night is at.

As we are on the Greenwich longitude line I assumed the shadow would run straight up and down the globe. But of course it can’t be if the Earth is tipped. That also explains why we have seasons in the North and South hemispheres.