lunar highlands

Our moon has two faces. One is the familiar man-in-the-moon side that always faces Earth. The other side is mountainous and heavily cratered, possessing a thicker crust with almost none of the large impact basins we see as dark maria on the Earth-facing side. The giant impact theory for the origin of the moon – that a Mars-size object hit the Earth and the debris coalesced into our planetary companion – has been controversial since it was first proposed. Will adding another impact help? It all depends on what one means by “scientific progress.”