Tuesday, May 01, 2012

Knapsack 5-10-12

Notes From My Knapsack – Granville Sentinel 5-10-12
Jeff Gill

Looking up, carefully

We have a wonderful collection of ancient Native American earthworks here in Licking County, and most of them seem to have some plan or design in them to relate to the heavens.

Solstices and equinoxes and lunar cycles and the path of the Milky Way: all of these are built into the epic architecture of the two thousand year old and thousand year old works of art and engineering that dot our hilltops and sprawl with purpose across the valley floors.

Humanity has always looked to the sky for understanding, because at the very least, regular recurring cycles place themselves in reassuring contrast to the strangely unexpected fluctuations of the weather. The sun's rise point steadily marches up and down the eastern horizon, and days get longer for half the year, shorter for the other half, and then repeat the whole process again. It's comforting, and a very real point of stability, even as the human body ages, as generations pass, and the output of the land in plants and animals goes from feast to famine.

There's the naked eye observation and recording that any person with a fixed abode and a stick to make marks in, or even to poke in the ground, can keep track of and make predictive sense from. Then there's the higher order record-keeping and mathematics that we see in the lunar observatory aspects of the Newark Earthworks, and specifically at the Octagon.

A further step towards understanding came with lenses, and telescopes, Galileo's observations and Copernicus' insights. It wasn't until the 17th century that Johannes Kepler began to take this sort of work, done for millennia by attentive sky-watchers around the world, and use the growing power of mathematics to calculate a level of detail about the Solar System that opened up even more insights into the working of the cosmos.

Kepler calculated that the planet Venus should cross directly in front of the blazing solar disc itself, and that a careful observer might be able to bring some scale for the universe down to our planet's surface, with some careful timings and observations from two widely separated locations, in just a very few years. Sadly, he did not live to see that day himself, but his prediction lived on.

From that first prediction in 1631, there was first observation in 1639 that began the process of measuring the vast distances of space through the parallax of two separated viewing points on our planet, leading to the "astronomical unit" from the Sun to Earth. More recently, with the 2004 viewing, we're beginning to calculate how to identify planets orbiting distant stars with what we learn "watching" Venus pass across the solar disc.

The distances, and odd orbits, mean that we can see this at intervals of about 243 years in full cycle, with two shots, eight years apart, in the middle. So the last viewings were 2004 and before that, 1882; in Ohio, our next shot is 2117 but not a good angle here, so we have to hold out to 2125.

So I'm hoping for clear skies (at least in the west) on the evening of June 5. I've ordered my eclipse glasses (they're quite cheap, but utterly necessary), and will drag my family atop Alligator Mound in Bryn Du Woods at about 6 pm. The "show" begins over the next half-hour, and continues, sadly for us, just until sunset. The crossing of the Sun by Venus takes about six and a half hours.

We won't be doing science ourselves that evening, but we – and you? – will be sharing in what I think is a very human endeavor. C'mon up, I may even have one extra pair of eclipse glasses. Kids, don't look at the sun without special protection!

I'll bet they said that 2,000 years ago, too.

Jeff Gill is a writer, storyteller, and supply preacher around central Ohio; tell him your cosmic tale of wonder at knapsack77@gmail.com or follow Knapsack @Twitter.

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