I've always wondered this same thing ever since I was fascinated as a child by the lurid green photographs of Ganymede (Jupiter) and Enceladus (Saturn) from Voy

I've always wondered this same thing ever since I was fascinated as a child by the lurid green photographs of Ganymede (Jupiter) and Enceladus (Saturn) from Voyager 2, only to later discover that they're false color images.