What are the Lunar Mansions (Manazil) and their relevance to calculating direction?
Chapter on Facing the Qiblah
Al-Mughni
Book of Prayer
Primary text
There are twenty-eight Lunar Mansions, including Al-Saratan, Al-Batin, Ath-Thurayya, Ad-Dabaran, Al-Haqa, Al-Hana'a, Adh-Dhirā', An-Nathra, At-Taraf, Al-Jabhah, Al-Zubrah, As-Sarfah, Al-'Awa', As-Sumaik, Al-Ghufr, Az-Zubana, Al-Iklil, Al-Qalb, Ash-Shawlah, An-Na'im, Al-Baldah, Sa'd Adh-Dhābih, Sa'd Bul'a, Sa'd As-Su'ūd, Sa'd Al-Akhbiyah, Al-Far' Al-Muqaddam, Al-Far' Al-Mu'akhkhar, and Batn Al-Hūt. Fourteen of these are Northern (Shamiyyah), rising slightly north of due east, starting with Al-Saratan and ending with As-Sumaik. Fourteen are Southern (Yamaniyyah), rising from due east or slightly south of it, starting with Al-Ghufr and ending with Batn Al-Hūt. For every Northern mansion, there is a corresponding Southern one such that when one rises, its counterpart sets. The Moon descends into one mansion nightly, moving to the next the following night, as mentioned in the Quran: "And the moon We have ordained for it stages until it returns like the old dried date stalk" (Quran 36:39).
Supporting text
The Sun remains in each mansion for thirteen days, completing a full solar year upon returning to its initial mansion. Four of these mansions are present between sunset and sunrise, and an equal number between sunrise and sunset. The dawn period corresponds to two mansions, and the sunset period corresponds to one mansion, which is one-half of the sixth part of the deepest night, the latter comprising twelve mansions. All rise in the east and set in the west, except the earliest Northern ones and the latest Southern ones, which rise from mid-east. When a Northern mansion rises, the person facing it such that the rising point is aligned with their left shoulder faces the Kaaba, similarly for the last Northern mansion. The earliest Southern mansion is near this alignment. The middle Northern mansions, such as Adh-Dhirā' and those adjacent, have risings inclined towards the north. The middle Southern mansions, like those near the Scorpion, An-Na'im, Al-Baldah, and the Sa'ds, have risings inclined towards the right. For the Southern star, the observer should align it before their left shoulder; for the Northern star, behind their right shoulder near it. If a mansion is intermediate (between setting points, defined by seven degrees above the horizon on both sides), the observer should face it directly. Stars near these mansions move with them and serve as confirmation.