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How To Define The Meridian Ecliptic? (Answer: Read On!)

Starry Night Pro Plus 8 allows me select the ecliptic meridian/meridian ecliptiic. I can't find the definition for such in the user manual or with a google search. Please advise.  Thank you.


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    Keiron Smith


    Please see the Starry Night SkyGuide > Guided Tours > First Night Out > The Ecliptic and the Zodiac.

    From the Starry Night > Help > User Guide

    SN8 User’s Guide Page 43 - Guides 1 (Coordinate Systems)

    The most commonly used systems are the alt/az and equatorial systems. You may also use ecliptic and, in Starry Night Pro and Pro Plus, galactic and extra-galactic.

    SN8 User’s Guide Page 44 - Guides 1 (Coordinate Systems)

    Ecliptic: This reference system uses ecliptic latitude and longitude as its two coordinates. Ecliptic latitude is similar to declination, except the line of 0° latitude is the ecliptic line (a pro- jection onto the celestial sphere of the plane of Earth’s revolution around the sun), instead of the plane of Earth’s equator. Notice the constellations that the ecliptic line passes through—these are the familiar Zodiac constellations. The sun will always be found directly on the ecliptic line, passing through the constellations of the Zodiac over the course of a year. Because the planets all move in almost the same place, they will all be found close to the ecliptic line. Ecliptic longitude has the vernal equinox as its zero point.

    SN8 User’s Guide Page 46 - Guides Layer in Starry Night Pro and Pro Plus

    Meridian: This displays the line of 0° “longitude” for the coordinate system in question. For the alt/ az system, this is the local meridian, a line running from due north along the horizon through the zenith, through to due south along the horizon.

    The User Guide is complete and comprehensive.


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    Lisa Foster

    Thank you Keiron for taking the time to answer.  I read this information and because it did not specifically use the term "ecliptic meridian", I lacked confidence. I did not want to assume.  You and others are far more knowledgeable in these matters. I am just a fledgling trying to find specific information based on a premise.  Thank you. As I read this again. My layman's definition would therefore be to my even less knowledgeable readers -the "ecliptic meridian" is that invisible line that is set as 0-degree latitude that passes through the celestial sphere called the plane of the Earth's revolution instead of the plane more commonly referenced using the Earth's equator.  Thank you.  Your reply is greatly appreciated.

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