- Who
- Pluto
- What
- 2,376.6 kilometre(s)
- Where
- Not Applicable ()
The largest dwarf planet by physical size is Pluto, which measures 2,376.6 km in diameter. This makes it marginally larger than the next-biggest dwarf planet, Eris, which has been calculated to have a diameter of 2,326 km (and no more than 2,348 km). Eris is slightly more massive, however, with a mass of 1.66 x 10^22 kg compared with 1.30 x 10^22 kg for Pluto.
To be classified as a Dwarf Planet, a body has to meet three key criteria. The first is that it must orbit the sun (it can't be the satellite of another Solar System body). The second is that it can't have fully "cleared its neighbourhood" – true planets have enough mass that they have either merged with or deflected away all other bodies in their vicinity. Finally, it must have been pulled into a more or less spherical shape by the force of its own gravity (a state known as hydrostatic equilibrium).
