"modern terminology" . . "planet" . "minor planets" . . "definition of ''planet''" . . . "definition of planet" . "definition of a planet" . "Definition of a planet" . "Definition of planet" . . . . "planet by current definitions" . "define the term ''planet''" . "Definition of planet" . . "what a planet is" . "definition of what is and is not a planet" . "regarded as planets" . . "nine planet" . "definition of the term ''planet''" . "define what a planet is" . "yet to be precisely defined" .