Talk:Meridian (geography)

message: Hello Everyone, I have made edits the meridian article. I have added references, and have also added sections such as "Pre-Greenwich" and "Measurement of Earth Rotation". I have also added parts to "Magnetic Meridian" and "Geographic". Please feel free to edit and ask questions. Lorchave (talk) 05:15, 26 July 2018 (UTC)
thread_title:  Comments 

message: In this paragraph:
The position of the meridian has changed a few times throughout history, mainly due to the transit observatory being built next door to the previous one (to maintain the service to shipping). Such changes had no significant effect. Historically, the accuracy of the determination of longitude was much larger than the change in position. The adoption of WGS84 as the positioning system, has moved the meridian 102.5 metres east of its last position (measured at Greenwich). The position of the current meridian is not identified at all in Greenwich but is located using a GPS receiver.
''
He says
 "the accuracy of the determination of longitude was much larger than the change in position."
Its apparent to me that the author intends to compare the endemic error in measurement with the size of the change in position in order to show that the changes in position had little significance.
However the sentence as found doesnt say this. I believe that he uses the word accuracy when he means to use the word error. If I were correct, it should read:
 "the error in the determination of longitude was much larger than the change in position."
It may have been a translation issue.  — Preceding unsigned comment added by 58.160.134.33 (talk) 04:17, 29 December 2014 (UTC)
thread_title:  I may have found an error in the text of this page. 

message: Anyone ever think of including the term for a line of latitude here?  —Preceding unsigned comment added by 69.159.219.48 (talk) 15:28, 20 September 2007 (UTC)
thread_title:  what are lines of latitude called? 

message: During my visit to Greenwich on the 3rd of May 2008 I took my GPS navigator (MIO 268, SW 3.2) and hoped to see the coordinate being exactly zero for longitude. I was surprised to see around 0.00147 degrees West, which I roughly calculated into approximately 150m (!) offset. The navigator had a good satellite reception and indicated a 1.6m accuracy. Also the altitude had quite an offset compared to the plaque on the observatory, but I did not make a note of that unfortunately.
How is it possible that the navigator has this enourmous offset and how is it possible that it works fine on the road, on which I believe it is closer to the 1.6m offset than the 150m offset. Does anyone have the same or other experiences?
(Marc van Beek, The Netherlands)  —Preceding unsigned comment added by 193.173.39.45 (talk) 09:42, 5 May 2008 (UTC)
replies: text: Marc, your GPS navigator was not at fault. Traditional, or historic, longitude and latitude differ from the longitude and latitude used by GPS systems (see the IERS Reference Meridian section of the Prime Meridian article for an explanation why). --Blake the bookbinder (talk) 05:59, 26 July 2008 (UTC)

text: No your GPS was not at fault.  The adoption of WGS84 moved the meridian east of its current location.  This does not appear to be documented anywhere in the Greenwich observatory complex (but I'm wiling to be proven wrong). 109.156.49.202 (talk) 14:45, 29 October 2011 (UTC)

text: March, your GPS navigator is right. The accepted meridian is now 200 m east of the conventional and symbolic Prime Meridian. Refer to: http://en.wikipedia.org/wiki/Meridian_(geography) 120.59.249.63 (talk) 15:37, 28 August 2013 (UTC)
thread_title:  What does your GPS navigator say? 

message: what is true meridian  —Preceding unsigned comment added by EverGreg (talk • contribs) 20:11, 12 January 2009 (UTC)
thread_title:  meridan 

message: An editor has asked for a discussion to address the redirect Central meridian. Please participate in the redirect discussion if you have not already done so.  -- 70.51.200.101 (talk) 05:43, 7 February 2015 (UTC)
thread_title:  Central meridian listed at [[Wikipedia:Redirects for discussion|Redirects for discussion]] 

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thread_title:  External links modified 

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thread_title:  External links modified (January 2018) 

message: No. The meridians are 
not perpendiculars with the small circles, but with the great circles (only East-West). The meridians are of course perpendiculars to Equator (cosinus ray=1). Carlassimo (talk) 21:56, 9 April 2020 (UTC)
replies: text: As I explained on my talk page, you are not correct. Bazonka (talk) 20:54, 15 April 2020 (UTC)
thread_title:  Meridians 

message: :
It's not obvious to me what cross and pass means here, and particularly whether the two verbs mean different things. —Tamfang (talk) 23:17, 17 July 2023 (UTC)
thread_title:  cross and pass