evaluations

Subsequent observations of Neptune in the late 19th century led astronomers to speculate that Uranus’s orbit was getting disturbed by another planet apart from Neptune. Ironically, even as Pluto was getting demoted, Ceres practically received a promotion. An earlier 21st century proposal for defining a planet would have accomplished more bonuses so by describing a planet as getting enough mass to be practically round and to orbit around a star without becoming a satellite of a planet or a star itself. Simply because Pluto’s moon Charon is virtually the size of the planet itself, astronomers sometimes refer to the two...