Book of Astronomy

Volume 1 of the Nature and Principles of Islam Nature and Principles of Islam original: 天方性理 (Tiānfāng Xìnglǐ). "Tianfang" (The Heavenly Direction) refers to Arabia or Islam, and "Xingli" refers to the Neo-Confucian study of Nature and Principle, here applied to Islamic cosmology.

...the night, on the other hand, is extremely cold. The nature of Mars is hot; if it were also to belong to the Day, it would then become extremely hot. In such a state, it could not achieve balance balance original: 平和 (píng hé); a state of equilibrium between opposing qualities (hot/cold, dry/moist) necessary for the existence of life., and all living things would fail to grow.

Among the Seven Luminaries, the Yang stars Yang stars original: 陽星 (yáng xīng); stars characterized by active, bright, or heat-producing qualities. generally belong to the Day, and the Yin stars Yin stars original: 陰星 (yīn xīng); stars characterized by passive, dark, or cool qualities. belong to the Night.

Only Mars is not so. Mars is indeed a Yang star, yet it belongs to the Night In traditional astrology, Mars is considered a nocturnal planet because its excessive heat is tempered by the coolness of the night, making its influence less destructive..