For those of us with no tangible navigation experience , encountering longitude and latitude co-ordinate is unremarkably the result of some hiccup using Google Maps . 40.722272 , -73.994194 ? What ? Where the heck is that ? Why are there so many digits after the decimal ?
We ’re here to help . And because one degree of longitude and line of latitude can in reality constitute very different distances , we might as well start with the very , very basics .
Latitude destine the Frederick North - south positioning . The equator is 0 ° , the Union pole 90 ° , and the south pole -90 ° . line of latitude pedigree drawn on a orb resemble a stack of circles of difference sizes , with the prominent at the equator .
Longitude specifies the earth - west lieu . For no ground other than an accident of history , the Prime Meridian , which runs through Greenwich , England , is 0 ° . Longitude lead up to 180 ° east and 180 ° west . Every longitude product line runs through both the N and south magnetic pole .
bonk these definition , you may pretty easily commute differences in longitude and parallel of latitude to distances — if you know the the wheel spoke of the Earth off the top of your foreland and can do trig on the fly . But here ’s the shortcut for everyone else .
At the equator , one degree of longitude and parallel of latitude both cover about 111 kilometer , or just under 70 miles . When we get forth from the equator , this starts getting cunning .
Longitude lines . Pearson Scott Foresman / Creative Commons
As you approach the rod , the aloofness represented by one point of difference in longitude gets to zero . This is easy to translate if you envision a globe painted with longitudinal argumentation , each one a ring passing through the magnetic north and south perch . At these perch — the “ ends of the Earth”—the line of reasoning are all scrunched up next to each other , and the distance represented by one degree of longitude is efficaciously zero . Here ’s atable summarizinghow one degree of longitude change from the equator to the poles .
But one degree of latitude stays , more the less , the same at 111 klick . The ever - interestingJason Kottkehas dug up acomment on Stack Exchange , which order us precisely what the digits in a latitude version can tell us . It ’s a fascinating mode to understand the plate of the co-ordinate system of rules and the things it help us locate .
The units digit ( one decimal degree ) gives a position up to 111 km ( 60 maritime mile , about 69 miles ) . It can say us roughly what large state or country we are in .
The first denary place is deserving up to 11.1 km : it can distinguish the position of one large city from a neighboring large urban center .
The 2d decimal place is deserving up to 1.1 km : it can separate one village from the next .
The third decimal place is worth up to 110 m : it can identify a large farming field or institutional campus .
The quaternary decimal place is worth up to 11 one thousand : it can identify a parcel of land of country . It is comparable to the distinctive accuracy of an undisciplined GPS unit of measurement with no hindrance .
The 5th decimal place is deserving up to 1.1 m : it distinguish trees from each other . Accuracy to this level with commercial-grade GPS units can only be achieved withdifferential correction .
The 6th decimal place is worth up to 0.11 m : you may use this for laying out complex body part in detail , for design landscapes , build roads . It should be more than good enough for tracking movements of glaciers and river . This can be achieved by taking conscientious standard with GPS , such as differentially corrected GPS .
Read the whole C. W. Post to find out what thirteen decimal shoes can mean . [ Stack Exchange ]
Top image : Strebe / Creative Commons
Latitude
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