The Moon's South Pole Hides a 4-Billion-Year-Old Secret
Recent
research has revealed significant geological insights about the Moon's south
polar region, uncovering evidence of ancient processes that shaped the lunar
surface over 4 billion years ago. Two major discoveries have emerged from
recent lunar missions and analytical studies: evidence of an ancient magma
ocean and new understanding of the South Pole-Aitken basin's formation
mechanism.
Ancient Magma Ocean Discovery
India's
Chandrayaan-3 mission, which successfully landed near the Moon's south pole in
August 2023, has provided compelling evidence for the existence of an ancient
magma ocean in this previously unexplored region (BBC, 2024). The mission's
Pragyan rover analyzed lunar regolith using an alpha particle X-ray
spectrometer during its 10-day operational period, collecting data from 23
different locations across a 103-meter traverse.
The
analysis revealed that the regolith composition near the south pole is
primarily composed of ferroan anorthosite, a mineral consistent with the lunar
magma ocean hypothesis (Nature, 2024). This discovery is particularly
significant because it provides the first direct evidence of magma ocean
remnants from the Moon's high-latitude southern region, extending previous
findings from equatorial and mid-latitude regions obtained during the Apollo
missions.
According
to the lunar magma ocean theory, the Moon formed approximately 4.5 billion
years ago following a collision between Earth and a Mars-sized body called
Theia (USA Today, 2024). The impact created a global ocean of molten rock
covering the lunar surface. As this magma ocean cooled and crystallized, denser
materials such as olivine and pyroxene sank to form the lunar mantle, while
lighter ferroan anorthosite floated to the surface, creating the Moon's crust.
The
uniform elemental composition observed by the Chandrayaan-3 mission supports
this formation model, demonstrating that the south polar region underwent the
same differentiation processes as other lunar regions. The rover's measurements
detected major and minor elements including sodium, aluminum, magnesium,
carbon, silicon, sulfur, potassium, iron, titanium, chromium, and manganese,
consistent with magma ocean signatures (ABC News, 2024).
South Pole-Aitken Basin
Formation Mechanism
New
research led by Jeffrey Andrews-Hanna at the University of Arizona has
challenged conventional understanding of how the Moon's largest and oldest
impact crater formed (Science Daily, 2025). The South Pole-Aitken (SPA) basin,
measuring approximately 2,500 kilometers in diameter and 6-8 kilometers deep,
was created by a massive asteroid impact roughly 4.3 billion years ago.
Previous
models suggested that the impactor approached from the south, but detailed
analysis of the basin's morphology indicates the opposite. Andrews-Hanna's team
determined that the basin's elongated shape narrows toward the south,
indicating that the asteroid struck from a northerly direction (Nature, 2025).
This finding was established by comparing SPA's configuration with other large
impact basins throughout the solar system that have independent evidence
regarding impactor trajectories.
The
corrected impact direction has significant implications for understanding the
distribution of excavated materials. The research indicates that the southern
rim of the basin, closer to the Moon's south pole, should contain a thick
accumulation of material excavated from the lunar interior during the impact
event. This material includes deep crustal and potentially upper mantle
components that were ejected and redistributed during the crater-forming
process.
Implications for Lunar Evolution and Artemis Missions
The
discoveries have important implications for understanding lunar evolution and
planning future exploration missions. The presence of ferroan anorthosite at
the south pole confirms that the magma ocean differentiation process operated
globally rather than being limited to specific regions. This supports models of
early lunar thermal evolution and provides constraints on the timing and
duration of magma ocean crystallization.
The
corrected understanding of SPA basin formation provides insights into the
distribution of KREEP (potassium, rare earth elements, and phosphorus)
materials on the lunar surface. These radioactive elements, which represent the
final products of magma ocean crystallization, show asymmetric distribution
between the near and far sides of the Moon (Space.com, 2025). The research
suggests that the SPA impact may have excavated late-stage magma ocean
materials that had accumulated beneath the far side crust.
For
NASA's upcoming Artemis missions, these findings indicate that the south polar
landing sites will provide access to some of the most scientifically valuable
materials on the Moon. The thick accumulation of deep-seated materials near the
SPA basin's southern rim offers opportunities to study lunar interior
composition and early solar system bombardment history (Cosmos Magazine, 2025).
Age Determinations and Solar
System Context
Recent
sample analysis from China's Chang'e-6 mission has provided precise age
constraints on major lunar impact events. Analysis of impact melt rocks
suggests that the SPA basin formed approximately 4.25 billion years ago, while
secondary impacts created features such as the Apollo basin at 4.16 billion
years ago (Chinese Academy of Sciences, 2025). These ages correspond to the
Late Heavy Bombardment period, when intense asteroid bombardment affected the
inner solar system.
The
timing of these impacts provides important context for understanding early
solar system dynamics and the conditions that allowed life to emerge on Earth.
The Moon serves as a preserved record of bombardment processes that also
affected Earth but have been obscured by geological activity and erosion.
Scientific and Exploration
Significance
The
discoveries at the Moon's south pole represent significant advances in
understanding lunar formation and evolution. The confirmation of magma ocean
remnants provides direct evidence for one of the fundamental processes in
planetary formation, while the refined understanding of impact basin formation
improves models of early bombardment history.
These
findings demonstrate the scientific value of exploring previously unvisited
regions of the Moon and highlight the importance of sample return missions for
advancing planetary science. The combination of remote sensing data, surface
measurements, and laboratory analysis of returned samples continues to reveal
new aspects of lunar history and evolution.
The
research underscores the Moon's role as a natural laboratory for studying
planetary processes that operated throughout the solar system during its early
history. As future missions return samples from the south polar region, they
will provide additional opportunities to study these 4-billion-year-old records
of lunar and solar system evolution.
References
ABC News. (2024, August 21). There was once an ancient ocean
filled with magma on the moon, scientists recently discovered. ABC News. https://abcnews.go.com/US/ancient-ocean-filled-magma-moon-scientists/story?id=112904789
BBC. (2024, August 21). Ancient ocean of magma found on Moon
south pole. BBC News. https://www.bbc.com/news/articles/cx2n0jgldn5o
Chinese Academy of Sciences. (2025, August 24). Study finds
Moon's Apollo Basin formed 4.16 billion years ago. Chinese Academy of
Sciences. https://english.cas.cn/newsroom/cas_media/202508/t20250825_1051352.shtml
Cosmos Magazine. (2025, October 8). How a giant asteroid
gauged out the Moon's largest crater. Cosmos Magazine. https://cosmosmagazine.com/space/astronomy/moon-south-pole-aitken-basin/
Nature. (2024, August 20). Moon had an ancient magma
ocean. Nature. https://www.nature.com/articles/d44151-024-00132-5
Nature. (2025, October 8). Southward impact excavated magma
ocean at the lunar south pole. Nature, 634,
589-594. https://doi.org/10.1038/s41586-025-09582-y
Science Daily. (2025, October 12). The Moon's south pole
hides a 4-billion-year-old secret. Science Daily. https://www.sciencedaily.com/releases/2025/10/251012054611.htm
Space.com. (2025, May 5). A giant crater on the moon may hold
remnants of an ancient magma ocean. Artemis astronauts could bring home samples
of it. Space.com. https://www.space.com/astronomy/moon/a-giant-crater-on-the-moon-may-hold-remnants-of-an-ancient-magma-ocean-artemis-astronauts-could-bring-home-samples-of-it
USA Today. (2024, August 20). India's lunar lander finds
signs a vast magma ocean may have once existed on moon's south pole. USA
Today. https://www.usatoday.com/story/news/nation/2024/08/21/india-chandrayaan-3-rover-lunar-magma-ocean-study/74860181007/
