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Looking for a Book - History of latitude & Longitude

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Looking for a Book - History of latitude & Longitude

Old 11th Feb 2019, 21:54
  #21 (permalink)  
 
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True, but it's still a great read.
And it explains the significance of accurate clocks in relation to solving the longitude problem.
After reading it, suddenly the whole process of position fixing with reference to a prime meridian fell into place.
Think of it whenever I look at my wristwatch - it's quite humbling really.
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Old 12th Feb 2019, 13:29
  #22 (permalink)  
 
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"Longitude" the book is a fabulous read...... better still is the twin DVD set, not surprisingly also called "Longitude"..... Actors Michael Gambon and Jeremy Irons. Superb movie. Still have to get my head about the relationship between time and longitude though...
I tried to attach a screenie of the DVD box, but to no avail, sorry, not too good at this computer stuff, being an old fart and all....
cheers
chris from oz

Last edited by Tuppy; 12th Feb 2019 at 13:52.
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Old 12th Feb 2019, 13:49
  #23 (permalink)  
 
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Originally Posted by WingNut60 View Post
Dymocks in Perth (Oz) have "Longitude" for $20 - in stock.
I'm heading in to town to pick up a copy tomorrow.
........
Got my book; paperback only.
I am sure it will make a good read but .....


I am a bit perplexed by a few lines in the Introduction referring to the Royal Observatory and the Prime Meridian.
..... The observatory also serves as the base for Greenwich Mean Time (GMT) and hence is the location where each day, year and century begins.
Unless I am geriatically confused, then I am fairly certain that each day, year and century actually begins somewhere out in the mid-Pacific.

I have assumed the position, pants around ankles and now waiting for the JB flack.
Incoming .........!!!!!!!!!!!!!!!!!!!!!!!!!!!
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Old 12th Feb 2019, 14:40
  #24 (permalink)  
 
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Originally Posted by WingNut60 View Post
Unless I am geriatically confused, then I am fairly certain that each day, year and century actually begins somewhere out in the mid-Pacific.
Well technically those wannabes in the Pacific celebrate New Year, the Millenium, etc when it's still the previous day according to GMT.

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Old 12th Feb 2019, 14:51
  #25 (permalink)  
 
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Originally Posted by DaveReidUK View Post
Well technically those wannabes in the Pacific celebrate New Year, the Millenium, etc when it's still the previous day according to GMT.
I understand your argument, but don't follow the logic.
Are you saying that all (-) zone offsets are not real and only become real once Greenwich passes around the back side (not backside) of the earth?
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Old 12th Feb 2019, 15:50
  #26 (permalink)  
 
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Originally Posted by WingNut60 View Post
I understand your argument, but don't follow the logic.
Are you saying that all (-) zone offsets are not real and only become real once Greenwich passes around the back side (not backside) of the earth?
Well, in a sense, I am.

Neil Armstrong, who wrote that introduction from which your quote comes, didn't reset his watch every 15 degrees when orbiting the Earth before setting course for the Moon.
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Old 12th Feb 2019, 16:15
  #27 (permalink)  
 
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Originally Posted by WingNut60 View Post
Got my book; paperback only.
I am sure it will make a good read but .....


I am a bit perplexed by a few lines in the Introduction referring to the Royal Observatory and the Prime Meridian.
..... The observatory also serves as the base for Greenwich Mean Time (GMT) and hence is the location where each day, year and century begins.
Unless I am geriatically confused, then I am fairly certain that each day, year and century actually begins somewhere out in the mid-Pacific.
I also was confused by this as I would have been surprised by Dava Sobel making such an error. So I checked my first edition copy of her book and find it does not even have an Introduction. Is it possible that later editions had an introduction added - possibly by another writer - that slipped by the editor?

I know that it is a common misconception, especially popular around the Millennium, that each new day (or millennium) begins at the Prime (Greenwich) Meridian. Of course new days begin their existence on the International Date Line in mid-Pacific (hence the name!). This would ideally lie exactly on the 180 degree longitude line but has been politically modified with various kinks and steps to avoid awkwardly splitting certain states or island groups.
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Old 12th Feb 2019, 17:27
  #28 (permalink)  
 
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Originally Posted by Dont Hang Up View Post
Is it possible that later editions had an introduction added - possibly by another writer - that slipped by the editor?
See my previous post. Armstrong wrote his intro for the 2005 reprint.

I doubt that it slipped by anyone.

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Old 12th Feb 2019, 22:29
  #29 (permalink)  
 
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I was holding the name of the quotee as a punch-line.

Makes you wonder if he really made it to the moon or whether that TV footage was done in a W-B studio.
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Old 13th Feb 2019, 07:20
  #30 (permalink)  
 
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Originally Posted by DaveReidUK View Post

I doubt that it slipped by anyone.
But regardless of authorship, it is still wrong.
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Old 13th Feb 2019, 08:55
  #31 (permalink)  
 
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Originally Posted by Dont Hang Up View Post
But regardless of authorship, it is still wrong.
No, it's just a question of which frame of reference is used, there's little point in arguing about which one is right or wrong.

Any airline or ship's captain will tell you that their day starts when the clock in Greenwich Park strikes midnight (well in winter, anyway).

Or any astronaut, come to that.
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Old 13th Feb 2019, 10:05
  #32 (permalink)  
 
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Time zones are both arbitrary and important at the same time. For convenience astronauts on the International Space Station use GMT (UTC), even though the launch and ground controllers are in Baikonur, Kazakhstan (+7hrs). Discussions about midnight and year-ends lead to heated (and mostly pointless) arguments.
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Old 13th Feb 2019, 10:34
  #33 (permalink)  
 
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It would be nice if the OP came back with some feedback to all the help and suggestions that has been given thus far
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Old 13th Feb 2019, 23:35
  #34 (permalink)  
 
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Originally Posted by GordonR_Cape View Post
Time zones are both arbitrary and important at the same time. For convenience astronauts on the International Space Station use GMT (UTC), even though the launch and ground controllers are in Baikonur, Kazakhstan (+7hrs). Discussions about midnight and year-ends lead to heated (and mostly pointless) arguments.
Not looking for an argument, but would appreciate any logical explanation (or opinion) of why the day, month or millenium would start anywhere other than at the date line (as per my post #25).
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Old 13th Feb 2019, 23:47
  #35 (permalink)  
 
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Originally Posted by DaveReidUK View Post
Any airline or ship's captain will tell you that their day starts when the clock in Greenwich Park strikes midnight (well in winter, anyway).
And the fisherman in Samoa he will have to wait another 11 hours before their day starts.
Conversely, for the copra harvesters on Christmas Island, they will have already experienced some 12+ hours of their day.

The only logical progression that my mind can reconcile, is that the day started at the date line and then flowed in a westerly direction around the world.

Still waiting for an explanation of any alternative view.
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Old 14th Feb 2019, 00:10
  #36 (permalink)  
 
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Originally Posted by WingNut60 View Post
And the fisherman in Samoa he will have to wait another 11 hours before their day starts.
Conversely, for the copra harvesters on Christmas Island, they will have already experienced some 12+ hours of their day.

The only logical progression that my mind can reconcile, is that the day started at the date line and then flowed in a westerly direction around the world.

Still waiting for an explanation of any alternative view.
One is used for measuring distance from a meridian the other is used to measure time?

More here...

National Geographic-Prime Meridian
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Old 14th Feb 2019, 00:27
  #37 (permalink)  
 
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Thanks for that but it still doesn't address my question, or not in the context of Armstrong's statement :-
The observatory also serves as the base for Greenwich Mean Time (GMT) and hence is the location where each day, year and century begins.
Nothing given so far explains why they might begin at the Prime Meridian rather than at the International Date Line.

If it's a concept previously well explained then can someone please point me at that previous explanation.
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Old 14th Feb 2019, 02:04
  #38 (permalink)  
 
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The Prime Meridian and GMT are the points against which all other time measurements are referenced. From a scientific measurement point of view, each new day starts at midnight GMT at the Longitude of Greenwich. It is also true that each new day starts 12 hours earlier at the International Date Line.

GMT is not subject to seasonal adjustment although it is corrected by the addition or subtraction of leap seconds in order to keep agreement with atomic clocks and synchronise the slightly variable rotation of the Earth with astronomical references. The astronomical references selected are distant stars or galaxies that remain static in the sky with reference to the Earth at the same time every day. Given that the Sun, Earth and the rest of the Solar System are travelling through space at tens of thousands of miles per hour, the current references used are so very remote from the Earth that they appear at exactly the same point in the sky each day.

When the Greenwich Meridian was chosen as the Prime Meridian, a large proportion of world trade passed through London and the rest of the UK. For a while, the French used a rival system based on Paris as their Prime Meridian. The only thing of any importance in time and navigation measurement is that a fixed line of Longitude is agreed by common consent to be a reference point against which all other measurements are referenced.
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Old 14th Feb 2019, 02:29
  #39 (permalink)  
 
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Originally Posted by G0ULI View Post
........ each new day starts at midnight GMT at the Longitude of Greenwich. It is also true that each new day starts 12 hours earlier at the International Date Line. .............
And this is where I stumble while looking for logic.
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Old 14th Feb 2019, 03:58
  #40 (permalink)  
 
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Ten years ago, my daughter lived in Wellington NZ, which is 176 E and therefore, like the whole of Enzed, is in the UTC+12 timezone. During the Austral summer, they would add one hour to go onto Daylight Saving Time. I liked to point out to her, that UTC+13 puts NZ across the dateline and therefore they should have gone back a day as well!

I was living in Alberta at the time, which is MST (UTC-7) during the Austral Summer and therefore the time difference between us, when looking across the Pacific and ignoring the date difference, was only five hours, which is hard to comprehend until you look at a map
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