Taken by Apollo 8 crewmember Bill Anders on December 24, 1968, while in orbit around the Moon, showing the Earth rising above the lunar horizon. Note that this phenomenon is only visible to an observer in motion relative to the lunar surface. Because of the Moon's synchronous rotation relative to the Earth (i.e., the same side of the Moon is always facing Earth), the Earth appears to be stationary (measured in anything less than a geological timescale) in the lunar "sky". In order to observe the effect of Earth rising or setting over the Moon's horizon, an observer must travel towards or away from the point on the lunar surface where the Earth is most directly overhead (centred in the sky). Otherwise, the Earth's apparent motion/visible change will be limited to: 1. Growing larger/smaller as the orbital distance between the two bodies changes. 2. Rotation of the Earth (the Moon's rotation is synchronous relative to the Earth, the Earth's rotation is not synchronous relative to the Moon). 3. Atmospheric & surface changes on Earth (i.e.: weather patterns, changing seasons, etc.).