 By the IAU's definition, there are eight planets in the Solar System; four terrestrial planets (Mercury, Venus, Earth and Mars) and four giant planets, which can be divided further into two gas giants (Jupiter and Saturn) and two ice giants (Uranus and Neptune).When excluding the Sun, the four giant planets account for more than 99% of the mass of the Solar System.Dwarf planets are bodies that are massive and warm enough to have achieved hydrostatic equilibrium, but have not cleared their neighbourhoods of similar objects.