Sunday, October 2, 2011

“If we go on the way we have,

the fault is our greed [and] if we are not willing [to change], we will disappear from the face of the globe, to be replaced by the insect.”
Jacques Cousteau


I have been on a globe trotting buying spree...not traveling just trotting around buying globes and globe influenced merchandise. So, that brings me to history as usual. Around 250 BC, the Greek mathematician Eratosthenes noticed that a post in the city of Alexandria, Egypt cast a shadow at noon on the summer solstice, the longest day of the year. But at the same time in Syrene, a town due south from Alexandria, a similar post did not cast any shadow. Why was this? Here comes the geometry!

Eratosthenes figured the sun must be shining its light at these two towns from different angles. The sun was directly above the post in Syrene, so the post did not cast any shadow. But the sunlight was shining toward Alexandria at an angle. This was because the earth's surface was curved, Eratosthenes reasoned.

By knowing the distance between the two cities and by calculating the angle of the pole to the shadow, Eratosthenes was able to apply geometric theory to determine the size of the earth. He figured out the diameter of the earth was 7,850 miles. He was only off a little. The earth's actual diameter is about 7,926 miles at the equator.

Many Greeks knew for sure the world was shaped like a globe. However, most of them didn't have any idea how this globe fit into the rest of the universe. Aristarchus, who lived in the 200s BC, said the earth revolved around the sun, but not many people believed him. Instead, they believed Claudius Ptolemy, an astronomer who said in 150 AD that the earth was at the center of the universe. Ptolemy said the moon, the sun, the planets and stars revolved around the earth in a series of circles. For another 1,400 years, many people mistakenly believed that this was a true picture of the universe. (Still there are those who think everything revolves around them also!)

In 140 BC, a Greek known as Crates of Mallus built what may have been the first globe in history. It is hard to picture what was on that globe, since the Greeks only knew what a small part of the planet looked like. They had never traveled to China, Australia or the Americas, so none of those places could have been on the globe.

Before European explorers and conquerors sailed across the oceans in the 1400s and 1500s, cartographers in Europe made globes. In 1492, Martin Behaim, a German cartographer, made the oldest globe that still exists today.
Behaim's globe is just under two feet in diameter and has six colors and over 1000 place names. The equator is shown divided into 360 degrees and the ecliptic is labeled with the signs of the zodiac. Also present are the tropics and the Arctic and Antarctic circles. Christopher Columbus was a mapmaker and during his four voyages he charted numerous maps of the lands he saw. Years later, the Dutch would become famous for making the best globes and maps. (Aha...my ancestors were good for more Heineken!)When the kings and queens of Europe gazed upon these wonderful spherical maps, they still imagined the rest of the universe circling around the earth. But in the 1500s and 1600s, Polish astronomer Nicolaus Copernicus, German astronomer Johannes Kepler and Italian astronomer Galileo Galilei debunked the myth that the earth was at the center of everything. They showed that the earth was actually a planet moving around the sun. Many religious leaders refused to believe these new ideas, and these men were cast out...and science still has a hard time being accepted all these centuries later.Sir lsaac Newton, came up with the first theory that explained the movements of the stars, the sun, the moon and the planets. Newton realized the force that causes an apple to fall from a tree to the ground is the same force that attracts the moon to the earth. Newton explained how this force called gravity holds the solar system together. Today, scientists are still getting more information about the universe and the laws of physics, but the rules discovered by Newton still give a good, basic description of the universe around us.

And I think the insects are preparing for their takeover. The spiders are obviously the early predators...check out this web in progress in the back yard!And the next time you see a globe, remember this planet we live on with kindness...like Mark Twain said, “Don't go around saying the world owes you a living; the world owes you nothing; it was here first.”

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