The Yutu-2 rover is on a roll. It's been exploring the far side of the moon since early 2019, as part of China's Chang'e-4 lunar lander mission. It now has its eyes set on a strange-looking cube-shaped object it spotted in the distance. Yutu-2's view of the cube is fuzzy and far-off, so the object's true nature should become clearer as the rover gets closer. The most likely explanation is a boulder. This part of the moon is pockmarked with impact craters, which can feature quite a bit of chunky debris. The Chang'e-4 mission represents the first surface exploration of...