Although its size has not been directly measured , Nix has been calculated to have a diameter of between 46 km ( if its geometric albedo is similar to Charon 's 35 % ) and 137 km ( if it has a reflectivity of 4 % , like the darkest Kuiper belt objects ) .
Although its size has not been directly measured , the moon is calculated to have a diameter of between 46 km , if its reflectivity is similar to Charon 's 35 % , and 137 km , if it has a reflectivity of 4 % , like the darkest Kuiper Belt Objects .