The document discusses the phases of the Moon and features seen on its surface. As the Moon orbits Earth, we see different portions of its sunlit side, changing from a thin crescent to a full moon monthly. Dark areas called "seas" are actually large, smooth plains of hardened lava. Galileo was the first to properly map the Moon using an early telescope, while Neil Armstrong became the first person to walk on the lunar surface in 1969 as part of the Apollo 11 mission.