Giant Impact

William sent in the link to https://phys.org/print468573722.html … astronomers have found fresh evidence for significant planetary disunity within a single explanet system suggesting, they theorise, that giant high speed collisions are partly responsible for planetary evolution. The impacts in question are posited to have occurred in Kepler -107 (an exoplanetary system discovered five years ago). However, giant impacts are thought to have had a fundamental role in shaping our own solar system – and the moon is possibly the result of such an impact. It may also account for Mercury's high density (we are told).