Latitude and Longitude for Total Dummies

Latitude and Longitude in DMS vs. DD

Although we don't have a cartographer or a geographer on the Antisocial Network team, we do have staffers who've done extensive work with mapping software and all that entails. As a result, they've absorbed more than a little knowledge of map projections and their use. We suspect that experience is much more on point than the life experience of Alan Li, who posted "How to Read Longitude and Latitude" to eHow.com (which Leaf Group moved to Sciencing.com)¹.

Li opens with a bold statement that uses one of the words later banned by Demand Media (parent of eHow), claiming that

"Longitude and latitude make up the most common and popular grid system used to navigate around the Earth."

We're pretty sure that neither "common" nor "popular" fits here – perhaps "familiar" would have been more appropriate, since almost everyone above the age of ten (except perhaps the OQ) knows about Lat-Long. That being said, Alan then manages to churn out 350-plus words on the topic, most of them more or less correct. He doesn't get around to mentioning much about how the system was derived or why it's clumsy for location and mapping, but hey – at least Li doesn't say anything monumentally stupid...
...until he gets to what he calls a "Tip" at the end of the post. That is where he earned this DotD nomination:

"Another popular format for longitude and latitude coordinates is the decimal degrees format, which expresses the coordinates using positive and negative values. For reference, a positive coordinate means that the coordinate is located either north or east while a negative coordinate means that the coordinate is located either south or west."

Alan did get the positive and negative conventions correct, but his explanation of decimal degrees completely missed the whole point of the difference between degrees-minutes-seconds (DMS) and decimal degrees (DD): DMS is based on sixty minutes per degree, sixty seconds per minute; and a second is about a mile long at the equator. In the DD system, 30 minutes equals 0.5 degrees, while 30 seconds equals 30/3600 (0.00833) degrees. It's a lot easier to throw around numbers like 45.37083° than 45°22'15'' – or at least we think it is...

That's Li's contribution to the Dumbass of the Day canon: he completely missed the point of the decimal degree system. We think your average fifth-grader would probably have been better off not reading Alan's brand of scientific inaccuracy when trying to get a straightforward answer.

¹ Leaf Group assigned one of their "cleanup team" to rewrite Li's post. She did a slightly better job, but still not all that great: watch for Rachelle's update to appear as a new DotD candidate in the future.

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