astronomer vs physicist

astronomer and physicist both are nouns.

Word	Noun	Adjective	Verb	Adverb
astronomer	Yes	No	No	No
physicist	Yes	No	No	No

As nouns, physicist is a hypernym of astronomer; that is, physicist is a word with a broader meaning than astronomer:

astronomer (noun)	physicist (noun)
a physicist who studies astronomy	a scientist trained in physics