minor planet vs heavenly body

minor planet and heavenly body both are nouns.

Word	Noun	Adjective	Verb	Adverb
minor planet	Yes	No	No	No
heavenly body	Yes	No	No	No

As nouns, heavenly body is a hypernym of minor planet; that is, heavenly body is a word with a broader meaning than minor planet:

minor planet: any of numerous small celestial bodies that move around the sun
heavenly body: natural objects visible in the sky

Other hypernyms of minor planet include celestial body.

minor planet (noun)	heavenly body (noun)
any of numerous small celestial bodies that move around the sun	natural objects visible in the sky