1. Synchronous Rotation: The Moon's rotation period (the time it takes to complete one rotation on its axis) is almost equal to its orbital period (the time it takes to complete one orbit around Earth). This means that the same side of the Moon always faces Earth, which is why we only see one side of the Moon from Earth. This phenomenon is known as "tidal locking" and is caused by the gravitational forces between the Moon and Earth.

2. Lunar Maria: The Moon's surface is marked by dark, relatively smooth regions called "maria" (singular: mare). These are ancient lava plains formed by volcanic eruptions that occurred billions of years ago. The maria cover about 16% of the Moon's surface and are concentrated on the near side of the Moon. They appear dark because of the iron-rich minerals in the lava that erupted onto the Moon's surface.