The Moon is Earth's only natural satellite and is about 238,855 miles away from our planet. It has a diameter of about 2,159 miles, making it the fifth-largest moon in the solar system. The Moon's surface is covered with craters, mountains, and flat plains called maria, which were formed by ancient volcanic activity. The Moon has a significant effect on Earth, particularly on ocean tides due to its gravitational pull. It goes through phases, including the new moon, first quarter, full moon, and last quarter, as it orbits Earth approximately every 27.3 days.