'Hidden Structures' Discovered Deep Beneath the Dark Side of the Moon
Scientists are unlocking secrets that have been buried beneath the moon’s surface for billions of years, revealing a far more dynamic history than previously thought.
The moon, Earth’s silent companion in the sky, has fascinated humans for millennia. From mythology and literature to telescopic observations and space missions, we've looked to the moon with wonder.
Now, thanks to the Chinese National Space Administration (CNSA), we’re beginning to understand the deep and complex story written in its ancient layers.
In a historic achievement, the CNSA’s Chang’e-4 mission landed on the far side of the moon in 2018. Often called the "dark side," not because it lacks sunlight, but because it's permanently turned away from Earth, this region had never been explored on the surface—until now.
Chang’e-4 was equipped with a suite of scientific instruments, including radar and imaging tools, to scan beneath the lunar surface and gather geological samples. The mission’s findings, made public in 2023 and published in the Journal of Geophysical Research: Planets, are offering the most detailed look yet into what lies beneath the lunar surface.
According to the data, the top 130 feet (roughly 40 meters) of the moon are made up of multiple layers of fine dust, fragmented rocks, and soil, known as regolith. These layers serve as a kind of time capsule, recording countless impacts from space debris and the slow evolution of the lunar surface.
Chang’e-4 landing (Onboard Camera View)
Hidden within these layers is a large crater, evidence of a violent collision with a massive object in the moon’s distant past. This discovery adds a significant piece to the puzzle of the moon’s impact history.
As Jianqing Feng, an astrogeological researcher at the Planetary Science Institute in Tucson, Arizona, explained, the crater’s presence and the surrounding layers point to a cataclysmic event that reshaped the local landscape.
But the surprises don’t stop there.
Beneath the crater, Chang’e-4’s radar identified five distinct layers of hardened lava—evidence of ancient volcanic activity that once shaped the moon’s interior and surface. These lava flows, now solidified, likely spread across the moon’s terrain during a period of intense volcanic activity billions of years ago.
Chang'e 4 Lander and Rover on the moon
This paints a picture of the moon as far more active in its early life than once imagined. Most scientists agree that the moon was formed approximately 4.51 billion years ago, likely when a Mars-sized planetesimal collided with Earth, ejecting a massive amount of debris into orbit.
This material eventually coalesced into what became the moon. In the hundreds of millions of years that followed, the moon was bombarded by meteors and asteroids, which created deep fissures in its crust.
At the same time, its interior was still hot, containing molten rock. “Just like on Earth, the moon’s mantle contained pockets of molten magma, which infiltrated the newly formed cracks thanks to a series of volcanic eruptions,” Feng explained.
What’s particularly intriguing is how the data shows the volcanic rock becomes thinner closer to the moon’s surface. This suggests that volcanic activity decreased over time, which aligns with the broader theory of lunar cooling.
"[The moon] was slowly cooling down and running out of steam in its later volcanic stage," Feng said. "Its energy became weak over time."
Scientists believe that volcanic activity on the moon ceased somewhere between one billion and 100 million years ago. Since then, the moon has been considered “geologically dead,” with little to no internal activity. However, the new findings suggest that this might not be entirely accurate.
