what is one controversy that is going on regarding this?
A number of Pluto-as-planet proponents have circulated a petition among astronomers to alter the definition
Definition of planet
A number of Pluto-as-planet proponents, in particular Alan Stern, head of NASA's New Horizons mission to Pluto, have circulated a petition among astronomers to alter the definition.
what is the definition of a planet? A planet is a body that orbits the Sun, is massive enough for its own gravity to make it round and has "cleared its neighbourhood" of smaller objects approaching its orbit how were they described during antiquity? Ancient Greek astronomers employed the term "asteres planetai" meaning "wandering stars", to describe those starlike lights in the heavens that moved over the course of the year and during the middle ages? Medieval and Renaissance writers generally accepted the idea of seven planets
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Definition of planet [SEP] Ongoing controversies
Despite the IAU's declaration, a number of critics remain unconvinced. The definition is seen by some as arbitrary and confusing. A number of Pluto-as-planet proponents, in particular Alan Stern, head of NASA's New Horizons mission to Pluto, have circulated a petition among astronomers to alter the definition. Stern's claim is that, since less than 5 percent of astronomers voted for it, the decision was not representative of the entire astronomical community. Even with this controversy excluded, however, there remain several ambiguities in the definition.