Talk:Zenith

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Is the article correct in saying that it's 90 degrees "altitude"? From the Wikipedia entry, altitude is a measure of length. Perhaps attitude is the right term? --Cluster 02:14, May 9, 2004 (UTC)

Contents 1 altitude or latitude? 2 Northern bias 3 Complete re-write of this page. 4 Zenith as highest point 5 Picture?

[edit] altitude or latitude?

IMHO the use of latitude in this article is incorrect. Altitude or elevation are the usual terms used to refer to the angle between an object and the horizon. For example, the article Horizontal coordinate system uses altitude. Sometimes the qualifier above the horizon is used when there is a possibility of confusion between the height above the horizon and above sea level.

[edit] Northern bias

This article is incorrect when read in the southern hemisphere. Htaccess 12:04, 9 May 2006 (UTC)

[edit] Complete re-write of this page.

Re-wrote the entire page to correct inaccuracies and provide a more solid scientific basis. Here is a discussion of the problems with the earlier contents and how this has been changed:

- Although the reference to a point is very common, it is much more appropriate to refer to the zenith as a direction. The latter can be defined and measured, the former is an immaterial concept hard to pin down when the celestial sphere has an infinite radius.

- The sky is a vague concept, inappropriate in this context, and the zenith direction at a point exists irrespective of whether there is an observer at that point. Avoid anthropocentric definitions. Similarly, the words above (and below) are unnecessarily vague in the context.

- The local horizontal coordinate system uses the zenith as one of its references axes. Using this fact as part of the definition of the zenith is a circular argument.

- Note that the definition of local meridian should be updated to be in line with the current definition of the zenith.

- The zenith-nadir line usually does not pass exactly by the center of the Earth: See vertical direction and vertical deflection for more information on this point.

- The Sun is not at the observer's zenith at the stated dates. On any particular day and time, the Sun is at the zenith of some location on Earth. I have removed this erroneous section entirely.

- Similarly, analytic geometry is not typically using the expression zenith angle, so I have not kept that paragraph. However, I have included information on the zenith angle (without the notation, which is purely arbitrary).

- Moved the statement about zenith being the highest point to the disambiguation page.

- Replaced the reference to Desktop Planetarium with references to published scientific glossaries, as well as an etymological dictionary.

Hope this helps. --Michel M Verstraete 23:14, 12 June 2006 (UTC)

Well its much more scientific now but also much harder for the lay reader to understand. Most people coming here probably want to come away with an understanding that the zenith is the point directly above where they are currently on the earths surface. The descriptions making use of gradients of the gravity field dont help the lay reader understand this. My point it the description is less useful for an encyclopedia if the reader has to understand physcis jargon to understand the article. Htaccess 17:35, 14 June 2006 (UTC)

With all due respect I don't think this is an improvement at all. I've been involved in science and astronomy for 20 odd years and I had to read it twice and still found it too technical. I have also never heard this definition but if it is strictly true even so, I think the usual laymans term should be first and foremost in the article, ie the Zenith is the point directly above your head in the sky and then perhaps put this further down in the text under a heading that identifies it as a stricter meaning.--Kalsermar 20:44, 14 June 2006 (UTC)

Point well taken (accessibility to a large public). However, the difficulty is precisely that the notion above is very vague. One of the purposes of an encyclopedia is to go beyond obvious or simplistic definitions and provide tools and means to stretch the mind. In any case, thanks for your comments: I have amended the text to make it easier to read and removed the dependency on the gradient, leaving only the gravitational force. Cheers, --Michel M Verstraete 23:19, 14 June 2006 (UTC).

Thanks for making the improvement! --Kalsermar 18:42, 15 June 2006 (UTC)

[edit] Zenith as highest point

There is some precedent for using zenith to mean the event of culmination. It's sometimes found in the term "lunar zenith," meaning the time or event when (or point where) the Moon is at its highest for the day; Wikipedia's own Tide article uses this phrase. This usage of "zenith" is permitted by Webster's NCD, sense 2, but a Google search using the query

"lunar zenith" -caravan -berth -"lunar zenith angle" -"lunar zenith distance"

finds no more than 80 distinct matches. As I did not find much evidence that this sense of the word is in wide use, I'll just mention it here and not on the main Zenith page.

(Notice it was necessary to filter out "lunar zenith angle" and "lunar zenith distance" because these phrases refer to a zenith which is directly overhead, and so are not evidence of a concept of a non-overhead zenith). -- JEBrown87544 02:59, 4 January 2007 (UTC)

I always knew the word zenith by this meaning, as did most of those around me. It is also used this way in the first episode of the TV series Chef!. Tealwisp 19:43, 11 June 2008 (UTC) —Preceding unsigned comment added by Tealwisp (talk • contribs)

[edit] Picture?

I believe that a explanatory picture, both for this article and Nadir´s would be really nice! —The preceding unsigned comment was added by 200.185.233.207 (talk) 01:45, 21 February 2007 (UTC).

A request was made at the Graphic Lab for such an Image: your comments would be welcome. --Dave the Rave (DTR)talk 09:39, 16 August 2007 (UTC)