Going through the planets I changed the colours to those most similar, within the web safe area. The rule I chose was the the shadows used would be below the main colour used. That way, it would feel coherent. E.g
|  | 
| Main Colour | 
|  | 
| Shadow Colour | 
      CMYK                                                                                                                  CMYK & WEB
Below are the new and final colours of the planets below, both RGB & CMYK.









