astronomical vs astronomy

astronomical is not a noun while astronomy is a noun.

Word	Noun	Adjective	Verb	Adverb
astronomical	No	Yes	No	No
astronomy	Yes	No	No	No

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

astronomical (adjective)	astronomy (adjective)
relating or belonging to the science of astronomy
inconceivably large