Degrees and Meters for Dummies (Again)

latitude vs. longitude

The staffers at the Antisocial Network have elected one member (our most anal-retentive) to run a regular check on the source material of our DotD winners. If the winning post has been removed from the website, that staffer makes a note on the award page and also marks the citation in red boldface on the index page. Normally, that's the end of the story... but today's a little different: we had awarded a DotD to "Emile Heskey," only to find that Leaf Group had assigned one of its cleanup crew, Chris Deziel, to fix the Sciencing.com article "How to Convert Distances from Degrees to Meters." Chris failed.

In his original, "Heskey" explained that a "standard degree" (whatever that is) is 111.235 kilometers; and to convert degrees to meters, you simply multiply the "number of degrees" by that number and then by 1000 to get meters. Yeah, sure... As our staffer pointed out, that only works for degrees of latitude (or degrees of longitude very near the equator). Deziel decided to take things farther, and in the process completely botched it. According to Chris,

"If you know the longitudes and latitudes of two points, you can use this information to calculate the distance between them. The calculation is a multistep one, and because it's based on linear geometry – and the Earth is curved – it's approximate."

Hang on for a second, while we walk through Chris's calculation. According to Deziel, a degree of arc on the earth's circumference is approximately 111,139 meters. Therefore, to calculate the distance between any two lat-long points on the surface of the Earth, you

1. Calculate the difference in latitude and multiply by 111,139
2. Calculate the difference in longitude and multiply by 111,139
3. Use the Pythagorean Theorem to determine the length of the hypotenuse,

At this point, our staff cartographer barfed up her oatmeal. Deziel's "solution" is, for all intents and purposes, completely worthless. Why? Because the length of a degree of longitude gets smaller as you approach the poles: His 111,139 number is only valid at or very near the equator! Is Chris unaware that the earth is a spheroid? And that being round means that the length of a degree of longitude decreases with increasing latitude? Apparently not...

Deziel is often called in to "fix" some of the dumbassery posted by early eHowians, and for the most part, he does a workmanlike job of correcting botched content Leaf Group has moved to HomeSteady and Hunker. But this dreck? It's classic Dumbass of the Day material!  A word for Chris (and "Emile"): haversine.

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