EarthshineSunlight reflected from Earth illuminates the near side of the Moon the Sun cannot directly illuminate. Unlike the Sun, the Moon does not glow by itself but is only visible when illuminated by sunlight. During crescent moon, Earth blocks some sunlight that would at full moon completely illuminate the near side of the Moon and the Sun can only directly illuminate a part of this side of the Moon. Earth, however, also reflects some sunlight which then dimly illuminates the rest of the near side of the Moon, a phenomenon called earthshine.