For centuries, astronomers and observers have reported strange lights, glows, and flashes on the Moon — events that seem to appear suddenly and vanish within seconds or minutes. These elusive occurrences are known as Transient Lunar Phenomena (TLPs), and despite centuries of study, their causes remain mysterious.
Recent scientific discussions suggest two intriguing explanations: the release of radon-222 gas from the lunar interior, and electrical discharges across the Moon’s dusty, charged surface. Both mechanisms could help explain why the Moon occasionally flickers with unexpected light.
Radon-222 and the Case for Lunar Outgassing
The Moon may appear geologically dead, but evidence suggests it still experiences occasional outgassing — the release of trapped gases from beneath its crust. One of the most important of these gases is radon-222, a radioactive noble gas produced by the decay of uranium.
Radon-222 is ideal for study because it’s short-lived, with a half-life of just 3.8 days. If detected near the lunar surface, that means it must have been released recently. Scientists have observed areas on the Moon, such as the Aristarchus Plateau, where bursts of radon appear correlated with previous reports of transient glows and hazes.
The process may work like this:
- Gas builds up in subsurface pockets or fractures.
- A moonquake or thermal stress opens a small vent.
- The trapped gas escapes, carrying fine dust into the airless sky.
- Sunlight interacts with the gas and dust, creating a faint luminescence or brightening.
- The cloud dissipates quickly, and the light fades — a perfect recipe for a transient event.
These small gas releases suggest that the Moon’s crust is still shifting and evolving, even if slowly, and that small amounts of radioactive decay continue to generate measurable activity.
Electrical Discharges: Sparks Across the Lunar Surface
Another possible explanation for transient lights involves electrostatic activity. The Moon’s surface is constantly bombarded by solar ultraviolet radiation and solar wind particles, which can charge its surface layers differently depending on whether they face the Sun or are in shadow.
The sunlit side tends to build up a positive charge, while shadowed regions may become negatively charged. Along the boundaries — crater rims, mountain edges, or the lunar terminator — intense electrical fields can form. When the charge difference becomes great enough, it could discharge as a tiny spark or arc, momentarily producing a flash of light.
This same electrical charging can also cause lunar dust to levitate or move, especially near dawn and dusk. Charged dust clouds could reflect sunlight or scatter it in unusual ways, creating the glowing or mist-like effects sometimes observed.
Although these discharges would be faint and short-lived, they could explain TLPs seen from Earth as quick flashes or diffuse lights.
A Complex, Living Surface
It’s likely that no single process explains all transient lunar phenomena. Some may be caused by radon-driven gas releases, others by electrical discharges, and still others by meteoroid impacts or observational artifacts. Yet the repeated appearance of such phenomena in specific lunar regions hints at ongoing, subtle activity beneath the surface.
Studying TLPs could help scientists understand the Moon’s internal dynamics — its residual heat, its trapped volatiles, and the way its surface interacts with space weather. These phenomena also remind us that the Moon, while quiet and ancient, isn’t entirely dormant.
Looking Ahead
Future lunar missions may carry instruments capable of detecting radon, measuring electrical activity, and capturing high-speed optical images of the surface. If we can catch one of these mysterious flashes in real time, we might finally uncover the true nature of the Moon’s fleeting lights.
For now, the disappearing glows and sudden sparkles remind us that our nearest celestial neighbor still hides secrets — and that even in its stillness, the Moon remains alive with quiet, subtle energy.