Nav Question
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Joined: Jun 2000
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From: London
Nav Question
I was recently posed the following brain teaser by a mate at a pub quiz:
"What are the most Northerly, Easterly, Westerly and Southerly states in the US?"
The most Northern and Southern were, obviously, Alaska and Hawaii respectively. But, he went on to say that the most Westerly and Easterly State was Alaska as well.
His reasoning was based around the Aleutian Islands near the Russian coast. This island chain apparently stretches round so far that the Westernmost tip is actually further West than Hawaii. So far, so good.
However, he went on to say, the Islands cross the International Date Line and so are also further East than the East Coast. I think his reasoning here is wrong and probably stems from looking at a world wall map, which might give the impression that any point on the right side of the map are further East than points further to the left of the map (i.e the continental US).
As I understand it, the International Date Line is a time zone device only and would have no effect on your frame of reference for navigation. In other words, if I travel a short distance in a Westerly direction across the IDL then I am a short distance West of my starting position, rather than being a long way East of it!
Try as I might, I could not explain this to him. Does anyone have any simple way of clarifying my position which I can present on our next meeting?
Thanks
"What are the most Northerly, Easterly, Westerly and Southerly states in the US?"
The most Northern and Southern were, obviously, Alaska and Hawaii respectively. But, he went on to say that the most Westerly and Easterly State was Alaska as well.
His reasoning was based around the Aleutian Islands near the Russian coast. This island chain apparently stretches round so far that the Westernmost tip is actually further West than Hawaii. So far, so good.
However, he went on to say, the Islands cross the International Date Line and so are also further East than the East Coast. I think his reasoning here is wrong and probably stems from looking at a world wall map, which might give the impression that any point on the right side of the map are further East than points further to the left of the map (i.e the continental US).
As I understand it, the International Date Line is a time zone device only and would have no effect on your frame of reference for navigation. In other words, if I travel a short distance in a Westerly direction across the IDL then I am a short distance West of my starting position, rather than being a long way East of it!
Try as I might, I could not explain this to him. Does anyone have any simple way of clarifying my position which I can present on our next meeting?
Thanks
Joined: Aug 1998
Aviation Qualifications: ATPL
Posts: 6,623
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From: Ex-pat Aussie in the UK
Well, North and south are absolute directions, in that there is a North and South Pole, and the amount of "northness" 
of an object may be defined by its proximity to that pole.
East and West, however, are relative directions - as there isn't any "East pole" you have to define your reference point before you can label something as being "East" of that point. The 180° line of longitude (i.e. pretty much what the "date line" is) isn't accepted as a definition of "East"!
As your freind asked "What are the most Northerly, Easterly, Westerly and Southerly states in the US?" - then he has defined his reference point in the original qestion - the United States. The most Easterly State, by any conventional definition, is that State the most to the East of the Majority of the land mass, without travelling around the planet to get there.
Under your freind's definition, you travel East from New York and you eventually get to the Aleutian Islands, but travel further East and you get to California, or Texas or wherever.
of an object may be defined by its proximity to that pole.East and West, however, are relative directions - as there isn't any "East pole" you have to define your reference point before you can label something as being "East" of that point. The 180° line of longitude (i.e. pretty much what the "date line" is) isn't accepted as a definition of "East"!
As your freind asked "What are the most Northerly, Easterly, Westerly and Southerly states in the US?" - then he has defined his reference point in the original qestion - the United States. The most Easterly State, by any conventional definition, is that State the most to the East of the Majority of the land mass, without travelling around the planet to get there.
Under your freind's definition, you travel East from New York and you eventually get to the Aleutian Islands, but travel further East and you get to California, or Texas or wherever.
