Why One Side of the Moon Is So Different From the Other
NASA’s latest gravity study reveals why the Moon’s near and far sides are so different, uncovering secrets beneath its surface.
Why One Side of the Moon Is So Different From the Other
For as long as humans have gazed skyward, the Moon has fascinated us. But what we see from Earth—its familiar face—is only part of the story. The other side, forever hidden from view due to the Moon’s tidally locked orbit, has long remained a mystery. Now, thanks to groundbreaking research from NASA, scientists are peeling back the lunar curtain to reveal striking differences between its two faces—differences rooted deep beneath its surface.
Unveiling Lunar Asymmetry with Gravity
In a study recently published in Nature, NASA scientists introduced a cutting-edge gravity model that offers unprecedented insight into the Moon’s internal dynamics. Developed using data from the Gravity Recovery and Interior Laboratory (GRAIL) mission, this model tracks subtle shifts in the Moon’s gravitational field as it orbits Earth in an elliptical path. These fluctuations aren’t just mathematical quirks—they’re physical responses to Earth’s gravitational tug, a process known as tidal deformation.
This gentle “flexing” of the Moon has revealed a stunning truth: the Moon’s deep interior isn’t the same on both sides. Ryan Park, who leads NASA’s Solar System Dynamics Group, explains, “Our study shows that the Moon’s interior is not uniform. The side facing Earth—the nearside—is warmer and has been more geologically active than the farside.”
A Tale of Two Faces
The Moon’s nearside is easily recognizable by its broad, dark plains known as maria—formed by ancient volcanic activity. These vast, flat expanses of cooled lava give the Moon its signature look. In contrast, the farside is marked by rugged highlands and lacks the large lava seas that characterize the visible side.
The GRAIL data suggests this contrast isn’t skin-deep. Scientists estimate the mantle beneath the nearside is about 100 to 200 degrees Celsius hotter than its counterpart. This thermal imbalance may be due to the presence of radioactive elements like thorium and titanium—abundant on the nearside and largely absent from the farside.
Ancient Volcanism and a Hotter Core
So why is the nearside hotter? The answer may lie in the Moon’s volcanic past. Billions of years ago, intense volcanic activity on the nearside likely caused heat-producing radioactive elements to become concentrated there. Over time, these materials generated ongoing heat, keeping the nearside’s interior more dynamic.
The new gravity model offers the most compelling evidence yet to support this theory. By studying how the Moon’s gravitational field varies with its position in orbit, scientists can infer the structure and behavior of its inner layers—shedding light on processes that shaped the lunar landscape billions of years ago.
More Than Just the Moon
The insights from this research go beyond lunar science. In a parallel study also published in Nature, Park’s team examined Vesta, a large asteroid in the belt between Mars and Jupiter. Unlike the Moon, Vesta’s internal structure appears surprisingly uniform, with little evidence of a significant iron core. This contrast helps scientists better understand the diversity of planetary bodies in our solar system—and how differences in formation history can lead to vastly different internal makeups.
Why the Moon Still Matters
The Moon is more than just Earth’s silent companion. It stabilizes our planet’s axial tilt, helps regulate ocean tides, and even plays a role in sustaining life as we know it. As Park points out, “Our knowledge of the Moon has expanded through both human and robotic exploration, yet many questions about its deep structure remain unanswered.”
NASA’s renewed focus on lunar research, alongside missions like Artemis and India’s Chandrayaan-3, reflects a growing realization: understanding the Moon is key to unlocking broader mysteries of the solar system.
Conclusion: Gravity Is Telling a Deeper Story
The Moon may always show us the same face, but thanks to NASA’s GRAIL mission, we now know its hidden half holds vital clues to its fiery past and complex interior. As scientists continue to decode these gravitational whispers, each new discovery brings us closer to understanding not only the Moon’s formation, but the history of planetary bodies across the cosmos.
Our natural satellite still has stories to tell—stories written in rock, heat, and gravity, waiting to be read by those who dare to look deeper.
Disclaimer:
This article is based on publicly available research from NASA and other scientific sources. It is intended for informational purposes and does not represent official statements from NASA.
source : India Today