What are transient lunar phenomena?

For centuries, sky-gazers have reported seeing peculiar, short-lived events on the moon’s surface, from strange flashes of light to hazy glows and patches of unusual colour. These fleeting occurrences are called transient lunar phenomena (TLPs). A TLP can last anywhere from a few seconds to several hours before vanishing.

Scientists don’t know what they really are or why they happen, but they’ve interpreted the TLPs’ existence to mean the moon is more dynamic than they once believed.

People have documented reports of these mysterious events for a thousand years; even the Apollo 11 astronauts reported witnessing a luminous glow in 1969. The most common sightings include bright, star-like points of light, reddish or coloured glows, and some sort of mists obscuring the view. Some of the most active areas for these phenomena include the Aristarchus and Plato craters.

While scientists are still exploring the origins of TLPs, there are a few leading theories. One is the release of gases such as radon and argon from beneath the moon’s surface. This outgassing could be triggered by gravitational stresses or the heating of the surface, causing the released gas and dust to glow or reflect sunlight. Another likely cause is meteoroid impacts, which are frequent on the moon because it lacks a protective atmosphere. These high-velocity collisions can generate a flash of light.

Other possibilities include electrostatic phenomena, where lunar dust becomes charged and levitates, and disturbances in the earth’s own atmosphere that distort our view of the moon.