Iyini iplanethi?
I-International Astronomical Union (IAU) ichaze ngo-Agasti 2006, ukuthi iplanethi esimisweni sonozungezilanga ingumzimba wasezulwini: - lizungeza iLanga (inkanyezi eyinhloko yesimiso sonozungezilanga), - inesisindo esanele sokuthatha ukuma kokulinganisela kwe-hydrostatic (cishe eyindilinga), - likhulu ngokwanele ukuba amandla alo adonsela phansi asuse noma yiziphi ezinye izinto ezilinganayo eduze komzila walo ozungeza iLanga.