anchor: ParticleSystem:setSizes
  Sets a series of sizes by which to scale a particle sprite. 1.0 is normal size. The particle system will interpolate between each size evenly over the particle's lifetime.
  
  At least one size must be specified. A maximum of eight may be used.
  ParticleSystem:setSizes( size1, size2, size8 )
  size1 number The first size.
  size2 (nil) number The second size.
  size8 (nil) number The eighth size.