come up vs astronomy

come up is not a noun while astronomy is a noun.

Word	Noun	Adjective	Verb	Adverb
come up	No	No	Yes	No
astronomy	Yes	No	No	No

come up (noun)	astronomy (noun)
	the branch of physics that studies celestial bodies and the universe as a whole

come up (verb)	astronomy (verb)
result or issue
start running, functioning, or operating
gather or bring together
gather (money or other resources) together over time
bring forth, usually something desirable
come up, of celestial bodies
come to the surface
move toward, travel toward something or somebody or approach something or somebody
move upward
get something or somebody for a specific purpose
originate or come into being
be mentioned