Geocaching 101: Latitude and Longitude

[+icezebra11]

From the blog today:

 

Example N47 38.938, W122 20.887

 

"We’ve already established the latitude could be anywhere along the line that is 47 degrees, 38 minutes, and 938 seconds north of the equator. Now we are looking at the longitude, the second group of numbers. The longitude starts with a W, so we are moving west from the Prime Meridian 122, so twelve and 2/10 (or ⅕) lines of longitude. Then, we move a further 20 minute and 887 seconds, and we’ve arrived at our destination. Where the lines of latitude and longitude cross, that’s our location!"

 

If you moved 938 seconds north and 887 west, you aren't in the right location!  C'mon GS, you should know coordinate systems better than that.

[+captnemo]

noticed this in the email opps.

[+IceColdUK]

https://www.geocaching.com/blog/2021/01/geocaching-101-latitude-and-longitude/

 

I think anybody struggling with the concepts of latitude and longitude would only be more confused after reading this article. ?

 

How does this help?

 

Quote

Because the first number—which indicates the degrees—is 47, we know that it is 47 degrees, so four and 7/10ths lines of latitude above the equator.

 

(Ok, maybe if you have a globe on your desk, that only marks the 0, 10, 20, ... degree lines.)

[+Pontiac_CZ]

Yep, that "10-degree lines" concept is a bit confusing. I wonder why the author felt the need to create it and then operate with fractions...

[+baer2006]

10 hours ago, icezebra11 said:

From the blog today:

 

Example N47 38.938, W122 20.887

 

"We’ve already established the latitude could be anywhere along the line that is 47 degrees, 38 minutes, and 938 seconds north of the equator.

(emphasis added by me)

 

WTF?!? It really irks me, that even someone writing GS's blog doesn't know that "39.938" is not "38 minutes and 938 seconds"! Whoever did this should write 100 times "One minute consists of 60 seconds" ... in hand-writing, using an almost used-up pencil stump!

[+IceColdUK]

1 hour ago, baer2006 said:

 ... in hand-writing, using an almost used-up pencil stump ...

... in a soggy logbook!

[+lee737]

On 1/7/2021 at 1:36 AM, baer2006 said:

Whoever did this should write 100 times "One minute consists of 60 seconds" ... in hand-writing, using an almost used-up pencil stump!

Yes, back to Lackey school for someone.... or primary school maths?

 

[+Gome210]

29 minutes ago, lee737 said:

Yes, back to Lackey school for someone.... or primary school maths?

 

The latter, unless this was an April Fools Joke-in January?

[+icezebra11]

Looks like they got the message, I see the article has been corrected. 

[+IceColdUK]

7 hours ago, icezebra11 said:

Looks like they got the message, I see the article has been corrected. 

Yep, an improvement. ?

 

I still don’t get this though:

Quote

Each line that you see representing latitude or longitude is 10 degrees

Each line you see where?

[+Gome210]

15 hours ago, IceColdUK said:

Yep, an improvement. ?

 

I still don’t get this though:

Each line you see where?

Maybe they mean the lines on the map above it.

[+thebruce0]

I feel like geocaching coordinates would have been so much more easily understood if they just explained how the 2nd number of the lat / lon values is a decimal representation of minutes (0-60), and each degree is comprised of 60 minutes.  That can lead into the rabbit hole of understanding the other formats of GPS coordinates (like Google's Decimal Degrees having no minute value, and the even more odd-to-look-at Degree/Minute/Second format).

But yeah the initial math explanations when I read it initially were just whuuuuuut?

[+NYPaddleCacher]

On 1/10/2021 at 1:36 PM, thebruce0 said:

I feel like geocaching coordinates would have been so much more easily understood if they just explained how the 2nd number of the lat / lon values is a decimal representation of minutes (0-60), and each degree is comprised of 60 minutes.  That can lead into the rabbit hole of understanding the other formats of GPS coordinates (like Google's Decimal Degrees having no minute value, and the even more odd-to-look-at Degree/Minute/Second format).

But yeah the initial math explanations when I read it initially were just whuuuuuut?

 

It might be easier for some to understand if it is explained how those lat/long coordinates are applied to the physical globe.

 

Imagine drawing a line around the globe on it's surface and you'll get a circle.  There are 360 degrees in a circle.  If one starts at the equator and goes toward the north pole, it would start at zero degrees and reach 90 degrees at the north pole.  If the equator is at zero degrees, then going toward the south pole could be described as negative degrees with -90 degrees at the south pole.    With only 90 degree marks between the equator and the north/south pole, breaking each degree into 60 increments (minutes) allows for greater accuracy. and as a decimal value, to three places to the right of the decimal, accuracy down to 6' for so can be achieved.  The same visual representation can be show when turning the circle on it's side, with zero degrees at the Greenwich mean line, and traveling along the equator. 

 

When a lat/long value is expressed in decimal degrees (0 to +/- 90 degrees) it's fairly easy to visualize those coordinates on a globe, but simple understanding that each degree can be broken up into 60 minutes it's still fairly easy to understand.  

 

While Google does often use decimal degrees format, it's certainly not proprietary to Google.   Although we all see lat/long coordinates displayed as Degrees Decimal Minutes,  under the hood a GPX file contains lat/long coordinates in Decimal Degrees format (without hemisphere designators).  It's much easier to do coordinate math in decimal degrees.

[+thebruce0]

7 hours ago, NYPaddleCacher said:

While Google does often use decimal degrees format, it's certainly not proprietary to Google.

Yes I didn't mean to imply that it was. Just that it's probably most commonly seen on google maps.

 

Everything else, yep!