月球正面是月球永远朝向地球的半球，而相对的另外半球被称为月球背面。因为月球绕地球公转的周期和它绕着自己的轴心自转的周期相同，因此在地球上只能看见月球的一面，这种情形称为同步自转或是潮汐锁定。月球直接被太阳照亮，而绕着地球产生的外观变化称为月相。月球未被照亮的部分有时也能看到朦胧的影像，这是地球反照的结果。这反映了地球表面反射的阳光也会照亮月球的表面。由于月球的轨道有点椭圆并且对黄道平面倾斜着，因此产生天秤动，使得从地球上累计能观察到的月球表面总共达到59%（但在任何一个瞬间能看见的略少于一半）。

The near side of the Moon is the lunar hemisphere that is permanently turned towards the Earth, whereas the opposite side is the far side of the Moon. Only one side of the Moon is visible from Earth because the Moon rotates about its spin axis at the same rate that the Moon orbits the Earth, a situation known as synchronous rotation or tidal locking. The Moon is directly illuminated by the Sun, and the cyclically varying viewing conditions cause the lunar phases. The unilluminated portions of the Moon can sometimes be dimly seen as a result of earthshine, which is sunlight reflected off the surface of the Earth and onto the Moon. Since the Moon's orbit is both somewhat elliptical, and inclined to its equatorial plane, librations allow up to 59% of the Moon's surface to be viewed from Earth (but only half at any instant from any point).