Kungani iPluto ingeyona iplanethi?
I - IAU (International Astronomical Union) ibiza into ethile esimisweni sonozungezilanga ngokuthi iplanethi uma ihlangabezana nalezi zimfuneko ezintathu ezilandelayo: 1) Leyonto kumelwe izungeze iLanga. 2) Into kumelwe ibe nesisindo esanele sokuthatha ukulinganisela kwe-hydrostatic (ukuma okucishe kube yindilinga). 3) Leyondawo ihlanze indawo ezungeze umjikelezo wayo.  IPluto ihlangabezana nezimfuneko zokuqala ezimbili kodwa yehluleka ukuhlangabezana nesesithathu. Ngakho, iPluto iye yahlukaniswa njengeplanethi encane.