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| Latitude and Longitude |
 Title text: NGS and IERS are complaining that they left CLEAR instructions to set the washing machine to WGS84 (G2296) instead of WGS84 (G730). |
Explanation
When you wash clothes, particularly wool and cotton ones in hot water, they can shrink. Randall pretends (1) that the latitude and longitude lines shown on maps physically exist on the Earth, (2) that they're made of some material that shrinks when washed, and (3) that the Earth has been washed, causing the lines to shrink. It obviously wouldn't work as shown, given that the lines cross oceans, which are composed primarily of solutions of inorganic salts in water and are liquid (though this does not entirely rule out that a "Do not tumble dry" instruction has been ignored, instead, causing its own set of problems). On a similar note, the latlong grid would have to be made of an incredibly strong material, if it is able to squeeze into the Earths's surface, while at the same time prone to shrinking when washed. However, even ignoring all of this, the shrinking grid wouldn't actually dig into the earth: All the latitude circles (except the equator) form small circles circles and will simply slip to the north or south upon shrinking finding a new position where they will again fit. The longitude circles and the equator form great circles and could theoretically cut into the earth, however in practice small disturbances (e.g. from mountains and inclined terrain) would cause them to slip either westward or eastward.
The level of the seawater wouldn't be squeezed down under the lines and bulge outwards between them. Not counting tidal effects, tsunamis, and (relatively) small surface waves, the oceans assume nearly-constant levels, thus the shrunk grid would simply submerge without affecting the ocean surface. While the rock could theoretically be depressed this would then cause the oceans to flood the affected areas changing the coastline, which is not depicted. Also, the lines are conceptual, not physical, things. There are also 360 main meridians, while Randall's globe chooses to only present 18 of them (half of them invisible on the other side): All the main meridians and also all 180 latitude parallels (i.e. those with round numbers), would shrink in the same manner, leading to a much different shape than what Randall presents here. Additionally, there is an infinite number of non-main meridians and latitude parallels that can be used on maps as well: if all of them shrank evenly in the same way, the entire surface of Earth would be compressed into a denser form, but without any bulges.
The title text refers to the International Earth Rotation and Reference Systems Service (IERS, formerly called the International Earth Rotation Service), and the U.S. government agency the National Geodetic Survey (NGS). Both of these establish 3-D coordinate systems for the Earth. WGS 84 (World Geodetic System 1984) is one such coordinate system, with two more recent "realizations" numbered G730 (the first to use GPS measurements) and G2296 (the most recent update).
Transcript
- [An image of the Earth showing most of Europe, Asia, Africa, and the Indian Ocean, with horizontal latitude lines and vertical longitude lines looking like a balloon tied tightly with string - like the lines are squeezed down into the surface.]
- [Caption below the panel:] Bad news: NASA accidentally shrank Earth's latitude and longitude lines in the wash.
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