Why is lat/long "backwards?"

EdFred

EdFred

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So I was doing some coding - or attempting to for figuring out distances, headings, etc, and my question is...

Why do we do everything in cartesian math x,y and lat/long in y,x ?
 
Because y/x is just the graph turned sideways and if you're on the equator you're looking at everything sideways anyway and there are a lot more people on the equator than the North or South poles.
 
Because you have your chart set for north-up instead of track-up.
 
asicer said:
Because you have your chart set for north-up instead of track-up.
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I fly N/S much more often than E/W

The other than that's a pain in the ass:

"east" is 0º, and we measure degrees/radians/etc...CCW in math, but in the real world north is 0 and we measure CW.
 
EdFred said:
I fly N/S much more often than E/W

The other than that's a pain in the ass:

"east" is 0º, and we measure degrees/radians/etc...CCW in math, but in the real world north is 0 and we measure CW.
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The spatial reference is arbitrary, but easterly longitude (east of the Prime Meridian) is positive, and west is negative. If viewed from the south pole, then it would be clockwise.

I suppose whoever thought up the convention was laying in bed staring up in to space under an imaginary spinning globe.
 
Educated guess, but I suspect it is because we as navigators learned to measure latitude long before we figured out the longitude piece.
 
You're confused if you think that latitude and longitude is cartesian. Further, there are plenty of cartesian things that are given row major.
 
I didn't say L/L was cartesian, but when I attempt to find the heading from say New Orleans to Dallas and attempt to use sin/cos/tan I get a result of something in the neighborhood of 153º - not 297º.
 
I'll take a SWAG. Rene Descartes developed the Cartesian Coordinate system in the early 1600s. The algebraic X, Y, Z axes are his. I think celestial navigation and the construct of lats and longs were already in place and used by sailors (but not sure). Maybe Descartes wasn't concerned about the curving lat/long axes since his were linear, all 90 degrees off from each other.
 
Because mathematicians developed one and sailors the other? And we all know how sailors are. Right, Henning? :D
 
Spherical geometry is a beeottch. Navigation was easier back when the world was flat.
 
Sac Arrow said:
Spherical geometry is a beeottch. Navigation was easier back when the world was flat.
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Actually, the formula for GC distances isn't that bad, and that part of the coding is taken care of. But when all the current formulas are based on 0 being to the right, and positive numbers going CCW, it makes the heading formula a giant pain. When 0 is up and positive numbers are CW.
 
EdFred said:
Actually, the formula for GC distances isn't that bad, and that part of the coding is taken care of. But when all the current formulas are based on 0 being to the right, and positive numbers going CCW, it makes the heading formula a giant pain. When 0 is up and positive numbers are CW.
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Seems like a simple solution might be to translate CCW numbers to CW so the existing coding can use it?
 
Sac Arrow said:
Seems like a simple solution might be to translate CCW numbers to CW so the existing coding can use it?
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Or how about sticking a "-" in the formulae where appropriate? :dunno:
 
Maybe latitude is listed first because historically it was the first.

It was easy to measure latitude by measuring the altitude of the Sun at noon or by measuring the altitude of the star Polaris.

Measuring longitude was harder, and required precise chronometers. So it developed later.

So my guess is that at first there were only precise latitudes. Just one number. Then when a precise number for longitude came along it was tacked on to the end of the number everyone was already measuring precisely.
 
Fearless Tower said:
Educated guess, but I suspect it is because we as navigators learned to measure latitude long before we figured out the longitude piece.
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Probably. Though longitude was known about and described centuries before it could be measured accurately. Columbus' expeditions made some (very) rough attempts based on astronomical conjunctions, which can be timed independently around the globe.

The math convention is related to Euler sequences to describe an orientation. The azimuthal angle comes before the polar angle because you won't get parallel parallels without that. Note there is also a third "position" angle, essentially heading.

The geographers' convention is much older, and things like that never ever ever die no matter what. Some other examples are why electrons carry negative charge, why most of the world drives on the right side of the road, and stellar magnitudes. We still call the faintest stars we can make out with good eyes 5th magnitude, a nomenclature invented by Hipparcos some 2000 years ago. There are many other examples.
 
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Make a new convention. you are Ed Fred. :D:D

(actually a very interesting thought process you have going on Ed...)
 
Because the human ear likes a short beat followed by a long beat.

Tick tock, Yin Yang, Lat Long,
 
Much ado about nothing. Want to know the heading from X to Y? Simply go to Great Circle Mapper,com. Punch in origination and destination airports. They already did the math. :D
 
Norman said:
Much ado about nothing. Want to know the heading from X to Y? Simply go to Great Circle Mapper,com. Punch in origination and destination airports. They already did the math. :D
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Not the point. Plus I need to do more with the information.
 
Because Jimmy Buffet did not sing about changes in longitude.

Because changing your latitude can get you to a warmer climate. Changing longitude is far less likely to.

Because no one says they are going to give you some longitude.

We all love latitude.
 
SkyDog58 said:
Because Jimmy Buffet did not sing about changes in longitude.

Because changing your latitude can get you to a warmer climate. Changing longitude is far less likely to.

Because no one says they are going to give you some longitude.

We all love latitude.
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We have a longitudinal axis on our planes, but not a latitudinal one. 'Splain that!
 
EdFred said:
So I was doing some coding - or attempting to for figuring out distances, headings, etc, and my question is...

Why do we do everything in cartesian math x,y and lat/long in y,x ?
Click to expand...

Good question, because it makes for reasonably easy spherical trig in celestial navigation. The other thing is inertia, it's been done and taught this way for centuries. Everybody knows how to use it. Think about it, trying to go metric in the US has proved impossible, even though it would take a week at most for everyone to get over it.

So what method of reference would you suggest?
 
EdFred said:
We have a longitudinal axis on our planes, but not a latitudinal one. 'Splain that!
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well... I guess we can consider it to be the lateral axis... sounds close enough to me.... latitudinal... lateral... yep. And it is the axis which we pitch around and without pitch, we would never get off the ground. :D
 
Sac Arrow said:
The spatial reference is arbitrary, but easterly longitude (east of the Prime Meridian) is positive, and west is negative. If viewed from the south pole, then it would be clockwise.

I suppose whoever thought up the convention was laying in bed staring up in to space under an imaginary spinning globe.
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Almost, they were laying in bed imagining they were at the center of the earth looking up through the ship to the celestial sphere that moved around them. All of celestial navigation still works on the principle that the Earth is the center of the universe, and the celestial sphere rotates around us.
 
We operate in an X,Y,& Z axis spherical grid. I'm trying to figure out how one would better represent it in a two dimensional plane, or even a 3D holographic projection. :dunno:
 
alphabetical ordering
 
Henning said:
We operate in an X,Y,& Z axis spherical grid. I'm trying to figure out how one would better represent it in a two dimensional plane, or even a 3D holographic projection. :dunno:
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There is a theorem in topology that it is not possible to represent a sphere as a plane without making at least one pole. Unipolar coordinates aren't difficult, but they aren't that familiar and aren't obviously better. An example would be the stereographic projection, whose only pole is the antipode. Unlike the Mercator or even the closely related gnomonic projection, there is no relation to navigation.
 
MAKG1 said:
There is a theorem in topology that it is not possible to represent a sphere as a plane without making at least one pole. Unipolar coordinates aren't difficult, but they aren't that familiar and aren't obviously better. An example would be the stereographic projection, whose only pole is the antipode. Unlike the Mercator or even the closely related gnomonic projection, there is no relation to navigation.
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But you can't make celestial nav work that way, and that's why we have the system we do. That's why the first thing you have to teach people when teaching them celestial is that they have to forget the modern model of the universe, and think back in time when this all started and use the core of the Earth as the center of the universe. Once they are clear on that, the rest is pretty easy to grasp. The reason we maintain the system is inertia.
 
Henning said:
But you can't make celestial nav work that way, and that's why we have the system we do. That's why the first thing you have to teach people when teaching them celestial is that they have to forget the modern model of the universe, and think back in time when this all started and use the core of the Earth as the center of the universe. Once they are clear on that, the rest is pretty easy to grasp. The reason we maintain the system is inertia.
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You really treat celestial nav as geocentric?

We have to do the topocentric thing, especially when describing the Moon. The error can be several degrees. Geocentric isn't good enough when observing an object only 240,000 miles away, with your relative position varying by some 8,000. atan(1/30) = 6 deg.

The right ascension (and hour angle) and declination variables are defined as geocentric, but they have some half dozen corrections before they get applied to real instruments.

Blind pointing a telescope is the inverse problem to celestial navigation. They are very closely related.
 
As for why they are in the order they are is simple, the portable clock. Celestial Navigation began along the Silk Road where the navigator would have a square frame with a string across the middle which would run parallel to the horizon. In the middle of this is tied a string of arms length. As an apprentice navigator you would at dusk at major landmarks, trading opportunities, and karawansaris, hold out the frame so the bottom limb rested on the horizon and Polaris rested on the top limb. He did this by holding it up to his face, putting the string between his teeth, and stretching it out to the correct distance, then tying a knot in the string where his teeth would catch. He now had a latitude reference for that location to find that place again by heading from the last station towards the next place's knot latitude, the continuing east or west on it.

It wasn't until the 1750's that we got an accurate and portable time piece for determining longitude. The easiest way to determine longitude is through a "Noon Sight". You time multiple sights of the sun around Local Apparent Noon, then compare the time of the largest arc to the reference meridian (Greenwich) and apply a rate of 15° per hour to the difference and you come up with your longitude.

So that's why they came to be in that order, we had portable latitude measurements way before longitude.
 
MAKG1 said:
You really treat celestial nav as geocentric?

We have to do the topocentric thing, especially when describing the Moon. The error can be several degrees. Geocentric isn't good enough when observing an object only 240,000 miles away, with your relative position varying by some 8,000. atan(1/30) = 6 deg.

The right ascension (and hour angle) and declination variables are defined as geocentric, but they have some half dozen corrections before they get applied to real instruments.

Blind pointing a telescope is the inverse problem to celestial navigation. They are very closely related.
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The geocentric model is so much easier for people to wrap their heads around so they can work the problems. At least it was for me and the people I've taught. Both work if you just use the given techniques properly, but it makes it easier to spot your mistake when you add instead of subtract. If you work the almanac and H.O. 129 sight reduction system properly you will get the same result regardless, and that is what I teach to because that's what the USCG tests. Most of them will never pick up a sextant. I understand your point from a true math point of view, but I'm not teaching them math, I am teaching them how to get an Oceans endorsement.
 
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