Celestial bodies have long served as one of the richest sources of mythological imagination in the ancient world and in sacred texts, making them central to the study of cosmology and worldviews reflected in these traditions. This study, however, does not limit itself to a simple comparison of mythological motifs. Rather, it investigates how the Avesta and the Quran mythologize celestial entities—such as the sun, moon, stars, planets, comets, and meteors—in order to uncover the underlying worldviews that shape these portrayals. By analyzing the differences in myth-making across the two texts, the research demonstrates that the divergent modes of celestial representation stem from fundamentally distinct worldviews. The Avesta's entire dualistic worldview leads to very detailed mythologies for each and every cosmic element, while in contrast, in the Quranic cosmology, which is based entirely on a purely monotheistic worldview, we do not witness any of those mythologies, except in rare cases. In this way, the study highlights the close interrelation between worldview, cosmology, and myth-making, showing how each both influences and is shaped by the others.