Module talk:Location map/Archive 8: Difference between revisions

Revision as of 02:13, 4 July 2016

Revision as of 02:21, 8 August 2016

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:::No, I was changing my own comments.--[[User:LL221W|LL221W]] ([[User talk:LL221W|talk]]) 07:39, 4 April 2016 (UTC)

== Astronomical maps ==

Is it possible to modify the template (or create a similar one such as "Template:Location map astronomy/constellation or /star chart") that allows markers to be added to any [[commons:Category:Constellations maps/SVG|constellation map]]? Celestial coordinates, instead of using longitude and latitude, use [[right ascension]] and [[declination]].

Declination is essentially the same as latitude with astronomical objects being defined as between 0 and 90 degrees north or south of the celestial equator, the plane created by the earth's equator extended outward into the celestial orb. A star, galaxy, or nebula sharing the same declination as the earthbound observer's latitude will pass directly above the observer once a day. An observer at the north pole will always have the star [[Polaris]] overhead as the star has a declination of approximately 89 degrees north.

Right ascension differs from latitude in how is is measured. Lines of right ascension are defined not in degrees, minutes, and seconds, but rather in hours, minutes, and seconds. Hence, a difference of one hour in right ascension corresponds to fifteen degrees of arc and can be expressed as up to 12 hours east or west of the zero-hour datum--the celestial equivalent of the Greenwich meridian. That datum is defined at the vernal equinox, a point where the ecliptic crosses the celestial equator in the constellation Pisces and extending to the north and south celestial poles. This is the same point as the ___location of the sun when it crosses from the southern to the northern celestial hemispheres each spring on the earth's northern hemisphere.

An example where this would be useful is the star chart in the infobox of the article about the star [[Gliese 667]]. Currently, the display is hard-coded with the size of the chart and the circle depicting the star's position expressed in pixels. I'm not an expert in cartography, and I suspect that the astronomy wikiproject may need to rework the coding of their maps and the projections they use, but I'm sure the hard work would make editing articles much easier afterward.

Infoboxes of astronomy articles usually employ these templates to express the coordinates of a celestial object:

*{{tl|RA}}

*{{tl|DEC}}

Thanks. [[User:Fortguy|Fortguy]] ([[User talk:Fortguy|talk]]) 03:32, 16 April 2016 (UTC)

:{{ping|Fortguy}} It should be feasible to create something. Location maps are usually equirectangular projections (so latitude horizontal, and longitude vertical), but other projections can be used (see [[Template:Location map Russia]]). With regards to the star charts - what projection is used (or could be used), and what is the extent of the chart? If those facts are known, then it should be feasible to use ___location map coding. However, the calculations may fail entirely close to the poles.--[[User:Nilfanion|Nilf]][[commons:User:Nilfanion|anion]] ([[User talk:Nilfanion|talk]]) 00:26, 10 May 2016 (UTC)