The question of whether humanity has images of the Moon’s hidden face is a common public fascination, often phrased using the misleading term “dark side.” This persistent query stems from the fact that we on Earth only ever observe one hemisphere of our nearest celestial neighbor. The answer is yes; we possess a comprehensive photographic record of the entire lunar surface. This record began with grainy, pioneering snapshots and has since expanded to include continuous, high-resolution global maps of the unseen portion of the Moon.
Defining the Far Side
The reason a portion of the Moon’s surface remained unobserved for so long is a consequence of synchronous rotation, also known as tidal locking. The Moon rotates on its axis in the exact same amount of time it takes to complete one orbit around Earth, approximately 27.3 days. Because of this perfect timing, the hemisphere facing Earth is always the same, leaving a “Far Side” perpetually out of our direct view.
This Far Side is not perpetually dark. The Sun illuminates the entire Moon as it orbits, meaning both the near side and the far side experience a two-week cycle of daylight followed by two weeks of night. The popular term “dark side” is a misnomer, likely originating because this hemisphere was entirely “unknown” or “unseen” until the Space Age. In fact, the far side receives roughly the same amount of solar radiation as the side we view from Earth.
The First Images Captured
The mystery of the Far Side was finally solved in the middle of the 20th century by the Soviet Union’s space program. The historic breakthrough occurred on October 7, 1959, with the successful flyby of the Luna 3 probe. This mission was the first spacecraft to navigate around the Moon and photograph the unseen hemisphere, providing humanity with its initial glimpse of the hidden terrain.
The photographs were captured from a distance of about 63,500 kilometers and covered approximately 70% of the Far Side’s surface. The resulting images were noisy and of low resolution, but they were sufficient to reveal a striking difference from the familiar near side. This initial reconnaissance showed a surface dominated by mountains and craters, lacking the vast, dark plains that characterize the Earth-facing side.
Modern Imaging and Mapping
Since the initial, blurry images from Luna 3, modern spacecraft have provided continuous, detailed coverage of the entire lunar surface. NASA’s Lunar Reconnaissance Orbiter (LRO), launched in 2009, is one such mission that has revolutionized our understanding. LRO’s instruments have collected hundreds of terabytes of data to create high-resolution topographical maps.
These modern images confirm the stark geological asymmetry between the two hemispheres. The Far Side is heavily pocked with impact craters and is largely dominated by rugged highlands. It contains very few of the large, dark, smooth areas known as maria (lunar seas), which are widespread on the near side. Maria, ancient plains formed by volcanic activity, cover only about 1% of the Far Side, compared to 31% of the near side.
The Far Side also hosts the South Pole-Aitken Basin, a colossal impact structure measuring approximately 2,500 kilometers in diameter and 8 kilometers deep. This makes it one of the largest known impact features in the solar system. The Far Side’s crust is significantly thicker, averaging about 20 kilometers greater in depth than the near side, a factor thought to limit volcanic flows. Modern mapping efforts provide unprecedented precision, bringing the knowledge of the Far Side to the same level of detail as the near side.