I had not noticed that the scale bar on Google Maps constantly changes as you scroll around (not just zoom in and out) due to the Mercator projection. Interesting article.
You can read why that happens in the paragraph titled "Scale".
Here's an excerpt (given that Google tiles are 256x256 and at zoom 0 one tile covers the whole world):
"Intuitively its easy to see why the scale changes. Let's think about Google Maps zoom level 0. At zoom level 0 the world is fit into a 256 pixel wide image. But we know that the earth's circumference is the largest at the equator and dwindles down to zero at the poles. So as you move north or south away from the equator, the Earth has to be "stretched" to fit into the 256 wide bitmap. Thus as you move north or south the scale gets larger and larger because the same number of pixels on the screen are showing you a larger and larger percentage of the Earth's surface."
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I had not noticed that the scale bar on Google Maps constantly changes as you scroll around (not just zoom in and out) due to the Mercator projection. Interesting article.
Interesting tidbit: the scale only changes when you go north/south. At the same latitude, the scale will remain the same as you pan east/west.
You can read why that happens in the paragraph titled "Scale".
Here's an excerpt (given that Google tiles are 256x256 and at zoom 0 one tile covers the whole world):
"Intuitively its easy to see why the scale changes. Let's think about Google Maps zoom level 0. At zoom level 0 the world is fit into a 256 pixel wide image. But we know that the earth's circumference is the largest at the equator and dwindles down to zero at the poles. So as you move north or south away from the equator, the Earth has to be "stretched" to fit into the 256 wide bitmap. Thus as you move north or south the scale gets larger and larger because the same number of pixels on the screen are showing you a larger and larger percentage of the Earth's surface."