== Oblateness (Flattening) of Charon == 

 == Flattening or Oblateness == 
 The recent study DOI: 10.1126/science.aad1815 stablishes and upper limit for the flattening of Charon.  It estimates that the difference in Radii is less than 1%. This seems to me like a very conservative estimate if you consider that the Earth which has a 6 times faster rotation has a flatening of around 1/3 of 1%.  However, we cannot insert our own opinion and the cited source will have to prevail until proven otherwise.