* Earth's Rotation: The Earth spins on its axis, and this rotation is what causes the appearance of the sun and moon rising and setting.
* Longitude: The Earth is divided into lines of longitude that run from the North Pole to the South Pole. The moon rises first at locations with the *easternmost* longitudes.
* Location Changes: As the Earth rotates, the moon appears to rise over different longitudes, so the "first" location constantly changes.
In short, the moon rises first at the location on Earth that is furthest east at any given moment.
