Sunday, October 28, 2012

Longitude, Latitude: Terminology

Humans—or as Quark, the Ferengi, in Deep Space 9 used to say, hu‑mahns—are challenged in a three-dimensional world. It might just be that we come from a four- or four-plus-dimensional region of the cosmos where wishing is as good as going there, so who needs bothering with maps. It’s a different story here. Two posts on this site are very popular. One, called “Longitude,” is the all-time favorite; another, “The Astrolabe,” which deals with Latitude, is tenth. One wonders why. Perhaps people are confused—and count me in. I wrote those posts but occasionally a kind of baffled fog surrounds me. I am temporarily unsure again. What is it, again, that longitude measures? I think the lines run up and down. Does it measure north-south alignment. Wrong, WRONG. But let us get there.

The “long” in longitude has obvious meaning. Something that is long. The “lat” in latitude is less obvious. It comes from Latin and means width. But we don’t measure the lat of a table or of a football field. Now the maddening—and confusing—aspect of these terms is that in effect we use longitude to measure width, latitude to measure height, both from fixed points on the face of the globe.

Longitude measures distance from some fixed point to the east and west. Call it Eastwestitude. Those lines are numbered from 0 to 180. The zeroeth line runs through Greenwich, England north to south or the other way about—which tells us who ran the last undisputed world empire. To the left and right of that line, the Meridian, thus to west and east of it if your head is north, your feet are south, the numbers increase at equal increments on both sides until they meet again and merge in 180 exactly at the opposite point of the globe from Greenwich.

Latitude measures distances from the Equator to the north and south. Call it Northsouthitude. The Equator represents 0 Latitude. Numbers above and below it both increase until they reach 90 at the two poles. Is there some equivalent to Greenwich on the Equator the name of which everybody knows? Yes and no. There is such a place, but virtually nobody knows it. It is Ciudad Mitad del Mundo (Mid-World City) in Ecuador. I bring an aerial image of it here from Wikipedia (link). Notice the yellow line faintly visible in the middle of the picture. That’s the equator. In this town you can walk with your loved-one hand-in-hand, one of you walking in the northern, the other in the southern hemisphere, and your hands clasped in the mitad.




Now when it comes to mnemonics, the problems continue. Eastwestitude is a pretty decent, straightforward description. But notice that it lacks an O, the marker in lOngitude, to which it belongs. Similarly, Northsouthitude is handy, but it lacks the A that might link it to lAtitude. Gul darn it. Based on this I am sure that in some future time I’ll be struck again by the lightning of confusion. Longitude will be there like some hovering monster—and I won’t remember whether to go up or down or left to right. That’s when blogs come in handy. Or should I speak of blags?

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