The question of whether the Moon has lava is answered with a clear historical “yes” and a contemporary “no.” While the Moon is not volcanically active today, its history is marked by massive eruptions that reshaped its surface. This ancient volcanic activity created the most recognizable features of our nearest celestial neighbor, exploring a past filled with surface events that ended billions of years ago.
The Timeline of Lunar Volcanism
The Moon’s volcanic history began shortly after its formation, starting around 4.2 billion years ago. The most intense period occurred between approximately 3.8 and 3.0 billion years ago, known as the Upper Imbrian epoch. During this time, enormous volumes of low-viscosity lava erupted, flooding large impact basins on the Moon’s nearside.
The volcanism was fueled by residual heat from the Moon’s accretion and the early differentiation of its interior. Heat was also generated by the natural decay of radioactive elements like uranium, thorium, and potassium within the lunar mantle. This heat kept the mantle molten, allowing magma to rise through the crust.
Though the majority of activity ceased by 3.0 billion years ago, evidence suggests minor, localized eruptions continued much longer. Samples returned by the Chang’e-5 mission revealed volcanic glass beads dated to about 120 million years ago. This discovery indicates the Moon retained enough internal heat to sustain sporadic volcanism.
Identifying the Ancient Lava Flows
The most visible evidence of the Moon’s volcanic past are the large, dark plains known as the Lunar Maria. These vast areas are immense deposits of solidified basalt, a dark, dense volcanic rock. The Maria formed when lava flowed into enormous depressions created by ancient, large-scale impacts, smoothing out the lunar surface.
These dark plains contrast sharply with the lighter-colored lunar highlands, which are heavily cratered and composed primarily of anorthosite rock. The Maria are younger and less reflective due to their iron and titanium-rich basaltic composition. Lunar basalt is chemically similar to Earth’s oceanic crust but contains unique mineral differences and is nearly devoid of water.
Other striking features confirming ancient lava flow are the sinuous rilles, which appear like dried-up, meandering riverbeds. These formations are interpreted as the collapsed roofs of massive lava tubes or channels that transported molten rock for hundreds of kilometers. The largest of these rilles, like Vallis Schröteri, showcase the scale of these immense lava flows.
Why Volcanic Activity Ended
The primary reason for the cessation of volcanism is the Moon’s relatively small size, which led to a faster loss of internal heat. As the heat generated by radioactive decay slowly dissipated, the mantle began to solidify.
The cooling process caused the Moon’s mantle convection—the slow churning of molten rock that drives volcanism—to slow down and eventually stop. Without this internal engine to push magma through the crust, large-scale eruptions became impossible. The Moon’s lithosphere, its rigid outer shell, grew thicker and more stable, effectively sealing off the interior.
While the Moon is now considered geologically inert, it still experiences minor seismic events called moonquakes. These quakes are not related to active volcanism, but are primarily caused by the gravitational stresses of Earth’s tidal forces or by thermal expansion and contraction.