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Mapping What You Cannot See

When I was a boy I canada goose factory sale had a globe. I could take it in my hands, rest it on my canadian goose jacket lap, give it a spin canada goose uk outlet and look down on Africa, Europe, North America and Asia spinning by.

In buy canada goose jacket 1961 (I was 13), cosmonaut Yuri Gagarin left the planet canada goose coats and got high enough to look down Canada Goose Jackets on the real Earth canada goose store spinning beneath him. He was the first (followed by Alan Shepard and later John Glenn) cheap canada goose uk to uk canada goose outlet gaze canada goose uk shop with his own eyes on what we had over the centuries so carefully mapped, drawn and imagined. From 160 miles up, canada goose black friday sale you can take in cheap Canada Goose the whole boot of Italy, the Red Sea narrowing to Suez, North America tapering down to the isthmus at Panama, and the amazing thing amazing to me, anyway is that what we’d spent 2,000 years drawing in our heads was actually there. We’d gotten it pretty much right!

Of course, you say. Cartography is a science. What it describes should be there. And yet, I find myself Canada Goose Outlet a little surprised by our ability to measure, to extrapolate, to conjoin, to build a true whole from a gazillion little parts. It’s an enormous intellectual feat. And now, I’m happy to report, it’s been done again on a scale that boggles my mind. None at all. At exactly noon where I live, the southerner wrote, the sun Canada Goose online is directly Canada Goose Coats On Sale over my head, not a single degree north, south, east or west. For that moment, I am Canada Goose sale shadowless.

Me And My Shadow

Hmm, thought Eratosthenes, that doesn’t happen where I live. Here in Alexandria on the longest day of the year at noon, the sun still casts a slight shadow. That got him thinking: What if the Earth is curved? Maybe sunshine is falling straight to Earth, but the shadow I see in Alexandria canada goose clearance is telling me that I’m at a different angle to the sun than my friend canada goose coats on sale down south? Maybe these shadow differences are canada goose clearance sale telling us we are living on a giant sphere.

He measured the distance between Alexandria and Syene, Egypt, where his friend lived. Then, on the next solstice, he put a stick in the Alexandrian thecanadagooseoutlet ground, measured the shadow at noon and was able to calculate (using trigonometry, based on the different lengths of shadow) how big canada goose the Earth Canada Goose Parka might be.

What’s amazing is he got very close. He imagined an Earth bigger than the one we live on, but since we don’t know how Eratosthenes measured distances exactly, Canada Goose Online his calculations canada goose uk black friday were either 16 percent too big or just 2 uk canada goose percent too big. Either way, he was conjuring up an immense ball, hundreds of millions of times bigger than he was, and when Yuri Gagarin got to see what Eratosthenes had imagined, it turns buy canada goose jacket cheap out, Eratosthenes was pretty much right. Go figure.

(Come to think of it, that’s what Eratosthenes did. Using a stick, a shadow and his head, he figured out what he was standing on. On our good days, we humans are very, very good.).

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