What is a dwarf planet ?
In August 2006, the International Astronomical Union (IAU) defined a dwarf planet as a celestial body that :
- orbits the Sun, 
- has enough mass to assume a hydrostatic equilibrium (nearly round) shape,
- has not "cleared the neighbourhood" around its orbit,
- is not a satellite.
Below is an instruction that describes a task, paired with an input that provides further context. Write a response that appropriately completes the request.
### Instruction: What is a dwarf planet ?
### Input: 
### Response: In August 2006, the International Astronomical Union (IAU) defined a dwarf planet as a celestial body that :
- orbits the Sun, 
- has enough mass to assume a hydrostatic equilibrium (nearly round) shape,
- has not "cleared the neighbourhood" around its orbit,
- is not a satellite.</s>