By setting the earth into motion the Copernican revolution had opened a venue for the possibility of extraterrestrial life in other planets inasmuch as they were now “similar” to earth (principle of similarity). By the end of the eighteenth century, this possibility slowly evolved into a strong belief thanks to the theological “principle of plenitude,” which dictated that life had to be widespread in the universe inasmuch as it was the highest form of existence that reflected God’s power and mercy. When combined, these two principles of similarity and plenitude provided a strong ground for the belief in the multiplicity of habitable worlds and extraterrestrial life until the early twentieth century. However, by 1860s further scientific discoveries had already started to weaken the strength of this belief in the West, while the debate was still lively in the Ottoman Empire. This paper will explore articles appearing from 1870s onwards in Ottoman popular journals such as Hadika, Ulum, Hikmet, Mahfil, and Malumat as well as monographies published at the turn of the century. My preliminary research reveals striking similarities between the Western and Islamic debates. These debates subvert the classical assumption that religion opposed science by showing how theological convictions justified scientific studies in a highly speculative field. Furthermore, some religious arguments re-employed this already theologically-bolstered scientific hope for extraterrestrial life with the purpose of “rationalizing” the existence of supernatural entities as spirits and angels; hence, further complicating the relationship between science and theology at the turn of the century.