Gnomon (γνώμων) is an ancient Greek word meaning "indicator", "one who discerns," or "that which reveals." It has come to be used for a variety of purposes in mathematics and other fields.
Best regards Kevin Karney On 10 Aug 2012, at 16:21, rPauli wrote: > We have to define gnomon - as something perhaps common to all sundials. > It is information reflected off the device. Must a gnomon cast a shadow? > > > On 8/10/2012 7:41 AM, [email protected] wrote: >> Color calibration was the primary function, however these sundials - which >> are also on the previous Mars rovers - were in fact designed to also be >> used to show time and season. Originally they were meant to be placed on >> stationary landers. Since rovers can change direction and latitude, making >> permanent lines a problem, the solution was to superimpose time indicator >> lines on the images digitally so the dial can be read, as in this photo >> from the Spirit rover: >> >> http://www.nasaimages.org/luna/servlet/s/fb8nc5 >> >> Here is an article (in PDF) from 2003 describing the design and operation >> of the Mars sundials: >> >> >> http://www.astro.washington.edu/users/woody/MarsDial.Plan_Rept.Jan04.pdf >> >> >> Don Rogerson >> >> >>> David, >>> >>> On >>> http://wtvr.com/2012/08/03/nasa-mars-rover-curiosity-will-land-early-monday/ >>> you can read that de 'sundial' is not used to have information "to >>> calculate time of day, date, and seasons" but as an appliance to color >>> balance the photgraphies Curiosity made. >>> >>> >>> Willy Leenders >>> Hasselt in Flanders (Belgium) >>> >>> Visit my website about the sundials in the province of Limburg (Flanders) >>> with a section 'worth knowing about sundials' (mostly in Dutch): >>> http://www.wijzerweb.be >>> >>> >>> >>> >>> >>> >>> >>> Op 10-aug-2012, om 11:03 heeft [email protected] het volgende >>> geschreven: >>> >>>> Dear Diallists, >>>> I thought you might find this particularly interesting, sent to me by my >>>> USA-based son. >>>> >>>> http://mars.jpl.nasa.gov/msl/multimedia/interactives/learncuriosity/index-2.html >>>> then click on the arrow until you get to the description of the 'Back' >>>> Click on the sundial (near the top/middle) >>>> >>>> Also: >>>> >>>> http://www.pcworld.com/article/260579/mars_rover_curiosity_a_complete_guide_to_tagging_along_online.html >>>> >>>> >>>> >>>> In particular: >>>> https://twitter.com/marscuriosity >>>> https://twitter.com/sarcasticrover (unofficial I'm guessing :) >>>> >>>> David Brown >>>> Somerton, Somerset, UK >>>> >>>> --------------------------------------------------- >>>> https://lists.uni-koeln.de/mailman/listinfo/sundial >>>> >>> --------------------------------------------------- >>> https://lists.uni-koeln.de/mailman/listinfo/sundial >>> >>> >> --------------------------------------------------- >> https://lists.uni-koeln.de/mailman/listinfo/sundial >> >> >> > > --------------------------------------------------- > https://lists.uni-koeln.de/mailman/listinfo/sundial > --------------------------------------------------- https://lists.uni-koeln.de/mailman/listinfo/sundial
