We already know a decent amount about how planets form, but moon formation is another process entirely, and one were not as familiar with. Scientists think they understand how the most important Moon in our solar system (our own) formed, but its violent birth is not the norm, and cant explain larger moon systems like the Galilean moons around Jupiter. A new book chapter (which was also released as a pre-print paper) from Yuhito Shibaike and Yann Alibert from the University of Bern discusses the differing ideas surrounding the formation of large moon systems, especially the Galileans, and how we might someday be able to differentiate them.