For an orbit outside the Solar System, the plane through the primary perpendicular to a line through the observer and the primary (called the plane of the sky).[3]
Animation about nodes of two elliptic trajectories. (Click on image.)
If a reference direction from one side of the plane of reference to the other is defined, the two nodes can be distinguished. For geocentric and heliocentric orbits, the ascending node (ornorth node) is where the orbiting object moves north through the plane of reference, and the descending node (orsouth node) is where it moves south through the plane.[4] In the case of objects outside the Solar System, the ascending node is the node where the orbiting secondary passes away from the observer, and the descending node is the node where it moves towards the observer.[5], p. 137.
The line of nodes is the straight line resulting from the intersection of the object's orbital plane with the plane of reference; it passes through the two nodes.[2]
Look up anabibazon in Wiktionary, the free dictionary.
Look up catabibazon in Wiktionary, the free dictionary.
The symbol of the ascending node is (Unicode: U+260A, ☊), and the symbol of the descending node is (Unicode: U+260B, ☋).
In medieval and early modern times, the ascending and descending nodes of the Moon in the ecliptic plane were called the "dragon's head" (Latin: caput draconis, Arabic: رأس الجوزهر) and "dragon's tail" (Latin: cauda draconis), respectively.[6]: p.141, [7]: p.245 These terms originally referred to the times when the Moon crossed the apparent path of the sun in the sky (as in a solar eclipse). Also, corruptions of the Arabic term such as ganzaar, genzahar, geuzaar and zeuzahar were used in the medieval West to denote either of the nodes.[8]: pp.196–197, [9]: p.65, [10]: pp.95–96
The Koine Greek terms αναβιβάζων and καταβιβάζων were also used for the ascending and descending nodes, giving rise to the English terms anabibazon and catabibazon.[11][12]: ¶27
The image of the ascending and descending orbital nodes as the head and tail of a dragon, 180 degrees apart in the sky, goes back to the Chaldeans; it was used by the Zoroastrians, and then by Arabic astronomers and astrologers. In Middle Persian, its head and tail were respectively called gōzihr sar and gōzihr dumb; in Arabic, al-ra's al-jawzihr and al-dhanab al-jawzihr — or in the case of the Moon, ___ al-tennin.[14] Among the arguments against astrologers made by Ibn Qayyim al-Jawziyya (1292–1350), in his Miftah Dar al-SaCadah: "Why is it that you have given an influence to al-Ra's [the head] and al-Dhanab [the tail], which are two imaginary points [ascending and descending nodes]?"[15]
^anabibazon, entry in Webster's third new international dictionary of the English language unabridged: with seven language dictionary, Chicago: Encyclopædia Britannica, 1986. ISBN0-85229-503-0.
^"Gōzihr". Encyclopædia Iranica (iranicaonline.org). February 17, 2012. Vol. XI, Fasc. 2, p. 184. Retrieved March 28, 2023. Cf. Gochihr (Zoroastrianism).
^Livingston, John W. (1971). "Ibn Qayyim al-Jawziyyah: A Fourteenth Century Defense against Astrological Divination and Alchemical Transmutation". Journal of the American Oriental Society. 91 (1): 96–103. doi:10.2307/600445. JSTOR600445.
(Unicode: U+260A, ☊), and the symbol of the descending node is 
(Unicode: U+260B, ☋).
