בראשית, פרק א׳, פסוק ט״ז

Preparing the world for humanity and nature required the careful shaping and placement of the celestial bodies in the sky. Rather than creating new matter from nothing, God shaped the luminaries from the heavenly spheres that had already been brought into existence. He fixed them in the sky to fulfill their ultimate purpose: to cast the light that was created on the very first day down upon the Earth [ספורנו, רמב״ן, מלבי״ם].

A striking contrast appears in the description of these celestial bodies. Initially, they are presented as two great luminaries, but immediately afterward, they are divided into a greater one and a smaller one. The primary approach among commentators is that the text speaks in ordinary human terms, describing the world exactly as it appears to the naked eye. The sun and the moon are both considered great only in relation to the other stars, simply because they provide the most light to the Earth. This visual perspective is used even though, astronomically, there are stars far larger than the moon, and the moon possesses no independent light of its own, functioning merely as a murky mirror reflecting the sun. Between these two prominent bodies, the sun is the truly great luminary due to the sheer intensity of its light, while the moon is the smaller one, characterized by a light that constantly shifts and fades [אבן עזרא, רד״ק, שד״ל, רב סעדיה גאון].

Offering a different perspective, other commentators suggest that the initial pairing implies an original state of absolute equality [רש״י, הכתב והקבלה, תורה תמימה]. According to this tradition, the sun and the moon were first created identical in both size and brightness. However, the moon complained to God, arguing that two kings cannot possibly share a single crown. In response, God commanded the moon to diminish itself, transforming it into the smaller luminary. The sun, having heard the slight but choosing to remain silent, retained its original greatness and was even rewarded with additional light.

The purpose assigned to these bodies is to rule over the day and the night. This does not imply conscious authority, but rather a profound natural, physical, and climatic influence over the earthly realm. The sun governs the day by driving the forces of heat and dryness, which are essential for ripening fruits and sustaining daytime crops. Conversely, the moon governs the night by influencing moisture, controlling the ocean tides, and nurturing the specific plants and crops that thrive in the cold [העמק דבר, רלב״ג, חזקוני, רב סעדיה גאון].

Finally, the stars are introduced to complete the night sky. On a practical level, they work alongside the moon to illuminate the Earth during the night, a time when the overpowering light of the sun does not obscure them. On a deeper, conceptual level, commentators explain that after the moon was made smaller, God provided the stars to serve as a royal entourage. This vast heavenly army accompanies the moon as it rises and sets, given by God to comfort and appease it after its reduction. Some even suggest that these stars were formed directly from the scattered sparks of light that fell away from the moon when it was diminished [מזרחי, רא״ש, תולדות יצחק].