Figure: Ancient Greek astronomer Ptolemy with an Armillary Sphere
Caption: An imaginary portrait of ancient Greek astronomer Ptolemy (c.100--c.170 CE) with an armillary sphere: spherical model of the celestial sphere.
Further Explication:
In ancient Greek, the word Ptolemy used for the cloudy objects was "nephele" which became a loanword in Latin as nebula (Latin for cloud or fog). Note nebula (L.) = nephele (G.) = νηφηλη (G. letters).
Note, Ptolemy may NOT have been the original discoverer of nebulae, but he is the first person in the historical record to mention them. Maybe some earlier ancient Greek astronomer or some Babylonian astronomer or someone ever further back (maybe even in the Paleolithic (c.3.3 Myr--c.11,700 BCE)) was first.