Whatever your primary association to the heading of this post may be, the main characters in this story are elephants’ teeth and stars. Inspired by Jon Kalb’s book Adventures in the Bone Trade, I will discuss two aspects of the question: how old is this place or thing?
From my childhood, I remember the Galilean moons as tiny spots in my small telescope.
Still this view was enough to stir interest and to excite my fantasy.
It is good to see that viewed close-up, they are even more spectacular.
All I really want to say with this is that the Wikipedia page on Galilean moons has spectacular images of them.