For as long as humans have tilted their heads to gaze at the night sky, the Moon has been a constant companion—bright, familiar, and strangely comforting. Poets have penned odes to its silver glow, and scientists have pondered its mysterious origins. But despite centuries of observation, half of the Moon has remained shrouded in mystery. This is the far side of the Moon—a realm we can never see from Earth.
The far side isn’t “dark,” as it’s often mistakenly called. It gets just as much sunlight as the near side, but because the Moon is tidally locked, one hemisphere always faces us while the other eternally turns away. For centuries, this hidden face was unknowable. Then, technology intervened. Today, we are no longer blind to the far side. We’ve photographed it, mapped it, and even landed spacecraft there. But what we’ve found is something far stranger than anyone expected.
In this journey, we’ll explore the far side of the Moon—its alien landscape, its deep and ancient craters, and the mysteries hidden beneath its surface. What lies beneath the far side’s crust? And what do these secrets tell us about the Moon, Earth, and the formation of our solar system? Strap in. It’s going to be an incredible ride.
The Far Side: First Contact with an Alien Landscape
Until the 1950s, the far side of the Moon was left to imagination. Early astronomers could only guess what was there. Some envisioned lush alien forests (an idea quickly ruled out), while others thought it might look much like the side we see from Earth—gray plains dotted with craters. But the reality turned out to be far stranger.
In 1959, the Soviet Luna 3 spacecraft became the first human-made object to photograph the Moon’s hidden hemisphere. The images it sent back were grainy and crude by today’s standards, but they revealed something shocking: the far side was almost entirely different from the side we know. Unlike the near side, which is covered in large, dark maria (smooth basaltic plains), the far side was a battered, cratered landscape almost devoid of maria. It looked ancient, scarred, and untamed—a relic of a violent past.
Why was it so different? What had happened on the far side that hadn’t happened on the near side? Or vice versa?
Two Faces of the Moon: A Geological Puzzle
The Moon’s asymmetry is one of the biggest mysteries in lunar science. The near side is dominated by the maria—vast, dark plains formed by ancient volcanic activity. These smooth seas cover about 31% of the near side. On the far side, maria make up only about 1% of the surface.
Geologically, this makes no sense. The Moon is one object, formed from the same material. Yet the two hemispheres tell two vastly different stories.
One theory suggests that Earth’s gravitational influence played a role. The side facing Earth was kept warmer over billions of years by tidal forces, making its crust thinner. This allowed magma to break through more easily, creating the maria we see today. The far side, more insulated and geologically conservative, kept a thicker crust that resisted volcanic reshaping.
But the story may go even deeper than that.
Inside the South Pole–Aitken Basin: A Window to the Moon’s Heart
One of the most remarkable features on the far side is the South Pole–Aitken (SPA) Basin. Stretching 2,500 kilometers across and up to 8 kilometers deep, it’s one of the largest and oldest impact basins in the solar system. If Earth had a crater like this, it would stretch from New York to San Francisco.
The SPA Basin is not just enormous—it’s ancient. Scientists believe it formed over 4 billion years ago when a massive asteroid slammed into the Moon. This impact was so powerful it may have punched through the lunar crust into the mantle below. If we could access these deeper layers, we might uncover clues about the Moon’s interior—and by extension, its origin.
In 2019, China’s Chang’e-4 mission became the first spacecraft to land on the far side, touching down in the Von Kármán crater within the SPA Basin. Chang’e-4 carried a small rover, Yutu-2, which continues to explore the region, taking measurements of the soil, rocks, and radiation levels.
The data it’s sent back is tantalizing. Yutu-2 discovered materials that may come from the Moon’s mantle—something scientists have sought for decades. By analyzing these samples, researchers hope to unlock secrets about the Moon’s composition and formation.
The Mystery of the Far Side’s Crust: Thicker, Colder, and Older?
One of the biggest differences between the near and far sides of the Moon lies beneath the surface. The far side’s crust is significantly thicker than the near side’s. This disparity has profound implications for how the Moon evolved.
Scientists have proposed several theories to explain the thicker crust:
- Earth’s Heat Influence: Shortly after the Moon formed, Earth was a molten ball of fire, radiating intense heat into space. The Moon, locked in synchronous rotation, always showed one side to Earth. This near side may have been kept warmer, slowing crust formation. The far side, turned away from Earth, cooled faster, allowing a thicker crust to solidify.
- Double Moon Theory: An alternate theory proposes that Earth once had two moons. A smaller moon may have collided with the larger Moon, merging on the far side and creating the crustal thickness we see today. This could also explain the highlands and rugged terrain.
- Giant Impact Legacy: Another possibility is that massive impacts like the SPA Basin triggered crustal thickening on the far side, altering its geology on a massive scale.
Each theory points to a Moon shaped by violent forces and cosmic accidents—its history written in rock and regolith.
A Hidden Metal Blob: Something Strange Beneath the Surface
In 2019, scientists announced a shocking discovery: a massive, mysterious blob of metal buried beneath the SPA Basin. Using data from NASA’s Gravity Recovery and Interior Laboratory (GRAIL) mission, researchers found an anomalous mass at least five times larger than the Big Island of Hawaii. They described it as a “metal-rich anomaly,” weighing around 2.18 quintillion kilograms.
What is it?
One possibility is that it’s the remains of the asteroid that formed the basin—its core buried beneath the lunar surface. Another idea is that it’s dense material from the Moon’s mantle, drawn up by the massive impact.
Whatever it is, this buried mass hints at processes on the Moon far more complex than we once believed. It raises questions about how the Moon cooled, differentiated, and evolved over billions of years.
Water Ice and Hidden Caves: Potential for Future Exploration
Beyond rocks and craters, the far side may hold more practical treasures—like water. In permanently shadowed regions near the south pole, scientists have detected signs of water ice. These deposits could be invaluable for future human missions, providing drinking water, oxygen, and fuel for rockets.
Additionally, the Moon’s lava tubes—long, hollow tunnels formed by ancient volcanic activity—could offer shelter for future astronauts. These natural caves might protect explorers from radiation, micrometeorites, and the harsh temperature swings on the lunar surface.
The far side’s isolation from Earth’s radio noise also makes it an ideal spot for radio astronomy. A telescope placed on the far side could listen to signals from the early universe, free from human interference.
The Chang’e Missions: Pioneering the Far Side Frontier
China’s Chang’e program has led the charge in exploring the far side. After Chang’e-4’s successful landing, the mission provided the first in-situ data from the hidden hemisphere.
Chang’e-5 followed with a sample-return mission from the near side, bringing back lunar soil to Earth for the first time since the 1970s. Future missions may aim to collect samples directly from the far side, including material from the SPA Basin and beyond.
These missions are not just about national pride—they are part of a broader scientific effort to understand the Moon’s composition, history, and potential for supporting future human presence.
What Lies Beneath: The Moon as a Time Capsule
The Moon is a time capsule. Unlike Earth, it has no atmosphere, no weather, and no tectonic activity to erase its history. Every crater and rock records the story of the solar system’s early days.
By drilling deep into the far side, scientists hope to access ancient materials untouched for billions of years. These layers could hold clues about the late heavy bombardment—a time when asteroids pummeled the Moon, Earth, and other inner planets. They could also reveal the secrets of the Moon’s magnetic field, which once existed but mysteriously disappeared.
The Moon’s hidden side may even shed light on Earth’s own origins. Some of the same processes that shaped the Moon influenced early Earth. Studying one helps us understand the other.
The Future of Far Side Exploration: Humans on the Horizon?
NASA’s Artemis program aims to return humans to the Moon, with a focus on the south pole region. Private companies and international space agencies are also eyeing lunar missions. But landing on the far side poses unique challenges.
Because the far side is hidden from Earth, missions require relay satellites to communicate. China’s Chang’e-4 uses the Queqiao satellite stationed at a stable point in space to send data back home. Future human missions will need similar infrastructure.
Still, the allure of the far side is undeniable. It offers scientific riches, potential resources, and the promise of humanity’s next giant leap. Some scientists even envision building a base on the far side, a stepping stone to Mars and beyond.
Conclusion: Peering Beneath the Shadows
The far side of the Moon, once a blank space on our celestial maps, is now an open frontier. Its alien terrain challenges our understanding of how worlds form and evolve. Beneath its surface lies a history written in rock and metal—stories of impacts, volcanoes, and perhaps even ancient oceans of magma.
As we stand on the brink of a new era in space exploration, the far side calls to us. What lies beneath may not just reshape our knowledge of the Moon, but redefine humanity’s place in the cosmos.