I'm not into astronomy but the Brazilian observatory just gave a press release having found the first ever asteroid with rings. They say it solves a number of questions for them so thought it may be interesting to add here

Rings found round asteroid

This appears to be the main link in the information they have found:

"Such a sequence of events, on a much larger scale, may explain the birth of our own Moon in the early days of the Solar System, as well as the origin of many other satellites around planets and asteroids"