A number of people who've seen the annual lunar phase and libration videos have asked what the other side of the Moon looks like, the side that can't be seen from the Earth. This video answers that question. (Update: The video was selected for the SIGGRAPH 2015 Computer Animation Festival.)
Just like the near side, the far side goes through a complete cycle of phases. But the terrain of the far side is quite different. It lacks the large dark spots, called maria, that make up the familiar Man in the Moon on the near side. Instead, craters of all sizes crowd together over the entire far side. The far side is also home to one of the largest and oldest impact features in the solar system, the South Pole-Aitken basin, visible here as a slightly darker bruise covering the bottom third of the disk.
The far side was first seen in a handful of grainy images returned by the Soviet Luna 3 probe, which swung around the Moon in October, 1959. Lunar Reconnaissance Orbiter was launched fifty years later, and since then it has returned hundreds of terabytes of data, allowing LRO scientists to create extremely detailed and accurate maps of the far side. Those maps were used to create the imagery seen here.
In the first of the two viewpoints, the virtual camera is positioned along the Earth-Moon line at a distance of 30 Earth diameters from the Moon and 60 ED from the Earth. The focal length is equivalent to a 2000 mm telephoto lens on a 35 mm SLR, making the horizontal field of view about one degree. The view is consistent with what you might see through an amateur telescope at these distances.
In the second view, the virtual camera is much closer to the Moon, only 1.2 ED, versus 31 ED from Earth. The camera focal length has been reduced to 80 mm, giving a 25° horizontal field. The result is an Earth that appears much smaller, more closely resembling the way it would look to the eye from the surface of the Moon.
We know how the Moon looks from here on Earth. But what does it look like from the other side?
Well for one thing, we can also see the Earth.
The spinning Earth looms large in this time-lapse telescopic view, made possible by computer graphics. We're looking along the imaginary line connecting the Earth and the Moon. From this vantage point, the Moon will be full soon, but on Earth, it's a waning crescent.
The far side of the Moon has fewer of the smooth, dark spots, called maria, that cover the side that faces Earth. Instead, the far side is covered with craters of all sizes.
In this second perspective, we're much closer to the Moon, using a wide-angle lens that makes the distant Earth seem smaller. (music)
With our view fixed on the Moon, the rest of the solar system seems to dance and whirl around us. (music)
Before the Space Age, no one knew what was on the other side of the Moon. Since 2009, Lunar Reconnaissance Orbiter has been making some of the most detailed global maps of the Moon's surface, making it much easier for everyone to see what it's like on the other side.
(beeping) (beeping) (beeping)