the highlands are flat, relatively light-colored regions known as highland plains. Scientists debate whether these plains are impact craters in mountainous regions or the result of earlier volcanic lava flows.
The Moon orbits around the Earth once every 27.3 Earth days. Except for Charon, satellite of the peculiar planet Pluto, the Moon is by far the largest satellite in the solar system relative to its planet. Indeed, some scientists have suggested that the Earth and Moon are actually a binary planet system. Because of gravitational interaction between the two bodies, the MoonΓÇÖs rotation period is about the same as its period of revolution; the result is that the same side of the Moon always
