A conception about a globe

 

I had long wanted to possess a globe. I didn't have a dream that I would explore all over the world like Europeans of the Age of Discovery, organize corporations in all countries like Starbucks or conquer the world like fanatics sometimes make an attempt, but I used to keep my eyes on globes whenever it came into my view. Sometimes, after I had grown up, I used to visit the National Geographic Society to see globes.

A merit of globes is that this makes it easy to visualize how days and seasons change. And it makes us know the relative areas among contries, too. Maps that use a projection, a way of translating the three-dimensional surface to a two-dimensional picture to depict the surface of the Earth, are inevitably inaccurate though splendid methods like Winkel tripel projection are being proposed, not to speak of the Mercator Projection, the best-known and best-distorted world-map projection. Those merits were maybe a reason that I was attracted?

To good thing to watch with globes is a constellation. It is becuase a constellation also cannot avoid a distortion when making a two-dimensional map like just as a terrestrial globe. The above first picture's production has light sensors so when I turn off the lights, the blue LED kicks in and displays constellations over the globe. The celestrial globe can express the southern constellations which almost all maps don't or separately draw because of its distortion.

Nor is the celestial globe without shortcomings. All stars are very distant from Earth. Their distances vary, but they are all very far away. Because of that, their light can be 'considered' reaching the earth in parallel lines. (Excepting the Sun. The light of the Sun reaches the earth 'nearly' parallel. The sun's rays are not actually parallel, but so close to parallel lines that for all practical purposes, they are considered. We had learned in school that the sun's rays that reaches the Earth come from 'optical infinity'. But, you know, the distance between the sun and earth is not infinity(http://www.phy6.org/stargaze/StarFAQ2.htm#q37). So the altitude of the stars is the same as one's latitude on Earth. The Polaris become almost 90 degrees, which is straight overhead when at the north pole.

 

Apparent constellations at 66.5 degrees.

At 90 degrees.

 

And as time goes by, the constellations shift gradually to the west because of the Earth's orbit around our Sun. Consequently, this celestial globe cannot express real constellation we can see at a specific point.

Anyway, there's no doubt that it's a good production to see.