Consider the noun "Jupiter", either the Roman god or the giant gaseous planet in our Solar System.
The adjective is "jovian", entirely unrelated.
Is this a distinct class of adjectives? I suspect there are many more examples.
EDIT: Is it possible that "Jupiter" does not have an adjective? "Jupiterian"?
In most studies for astrophysics I've seen, the go-to adjective is "Jovian"....