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How far is...


Guest tnunnery

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Guest tnunnery

How far is 1/1000 of a minute?

 

That is, how far is:

N 30° 18.400 W 090° 40.500

from:

N 30° 18.400 W 090° 40.501

 

I assume 1/100 of a minute would be roughly ten times this distance. Would a difference of 1/1000 of a minute in latitude be the same as the difference 1/1000 of a minute in longitude?

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Guest Mengarelliott

Let's see if I can get this right...

 

Each degree of latitude covers 1/360th of the circumference of the planet. Each degree of longitude at the equator covers that same distance. However, at the poles, each degree of longitude covers no distance.

 

If we assume that the earth is a perfect sphere with a radius of 3963 miles, that means that each degree of latitude is 69.17 miles (or 365,204 feet). So each minute covers 1/60 of that: 6,087 feet. 1/1000 of a minute of latitude therefore covers 6.087 feet.

 

Longitude is more complicated. Here's the formula:

 

D = (3963 * 5280 * cos(Lat) * 2 * pi) / (360 * 60 * 1000)

 

Where D is the distance covered by 1/1000 of a degree of longitude (in feet) and "Lat" is the absolute value of the latitude.

 

You can shorten this to "6.087 * cos(Lat)" (Where have I seen that number before?)

 

That means, at 30° 18.400 (north or south), 1/1000 of a degree of longitude covers about 5.25 feet.

 

Mengarelliott

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