The Moon — Transient Lunar Phenomena: Five Centuries of Unexplained Lights

The Moon — Transient Lunar Phenomena: Five Centuries of Unexplained Lights

Overview

Transient Lunar Phenomena (TLPs) — also historically called Lunar Transient Phenomena (LTPs) — are short-lived lights, glows, colour changes, and obscurations observed on the Moon's surface by earthbound observers across more than five centuries. They are among the most consistently documented anomalies in the entire history of astronomy, observed by professional astronomers and amateurs alike, and they have never been fully explained.

The Historical Record

The TLP observation record begins long before the modern era:

• 1540: The earliest systematic TLP records in the NASA catalogue
• 1178 (June 18): The monk Gervase of Canterbury recorded what may be the oldest described TLP — five witnesses reported seeing the upper "horn" of a new crescent Moon "suddenly split in two" and glow with fire, writhing and pulsating
• 1650–1800s: Multiple documented TLP observations by professional astronomers including Sir John Herschel (son of William Herschel), who observed unexplained lights above the Moon during a lunar eclipse
• 1787: William Herschel himself observed three "volcanoes" on the dark side of the Moon — luminous points brighter than any volcanic activity that could plausibly persist

NASA assembled a catalogue of TLP observations. The number of documented events varies by catalogue:

• A 1968 NASA report by Barbara Middlehurst and Patrick Moore catalogued 579 events between 1540 and 1967
• Other catalogues cite 570+ events over the same period

Documented TLP Locations

TLPs are not randomly distributed across the lunar surface. They cluster at specific locations:

Location	Frequency	Description of phenomena
Aristarchus crater	Most frequently reported site	Reddish glows; blue light; luminous mists; flashes; the "blue gem" observed since 1992
Plato crater	Second most frequent	Glowing mists; transient lights; obscurations of crater floor detail
Alphonsus crater	Significant frequency	Reddish patches; a spectroscopic detection of carbon compounds in 1958 by Russian astronomer Nikolai Kozyrev
Kepler crater	Reported	Luminous phenomena
Grimaldi crater	Reported	Reddish colorations

The clustering of TLPs at specific sites — particularly Aristarchus, which accounts for nearly a third of all reported events — suggests a localised physical mechanism rather than random atmospheric or instrumental artefact.

Specific Modern Events

The Aristarchus Blue Gem (1992–present): In 1992, the Aristarchus crater was photographed showing a striking blue luminescence — now referred to as the "blue gem" or "blue light." This feature has been observed periodically since by ground-based and orbital telescopes. Some researchers have proposed it is consistent with a fusion reaction; others attribute it to unusual mineralogy reflecting sunlight in a specific way.

Nikolai Kozyrev's Spectroscopic Detection (1958): On November 3, 1958, Soviet astronomer Nikolai Kozyrev obtained a spectroscopic observation of Alphonsus crater during a reported TLP event that showed absorption features consistent with carbon monoxide or carbon dioxide gas. This is one of the few TLP events backed by spectroscopic instrumentation rather than visual observation alone. The finding suggests localised gas release from the lunar interior.

Scientific Explanations

The mainstream scientific explanations for TLPs include:

• Outgassing: Gas (primarily radon, carbon dioxide, or water vapour) released from the lunar interior through fractures, creating luminous phenomena when the gas interacts with solar radiation
• Electrostatic effects: The Moon's surface becomes electrostatically charged by solar wind; dust levitated by electrostatic forces near the terminator (the day-night boundary) could produce luminous effects
• Meteoroid impacts: Small impacts can produce brief flashes visible from Earth
• Photometric effects: Unusual reflection of sunlight from specific surface minerals or topographic features
• Atmospheric disturbance: Some historical observations may reflect Earth's atmospheric seeing conditions rather than actual lunar phenomena

Why TLPs Remain Anomalous

Despite these explanations, TLPs remain officially anomalous for several reasons:

• The clustering at specific sites is difficult to explain by random impact or atmospheric effects
• The frequency and character of Aristarchus events specifically have persisted for decades
• Kozyrev's spectroscopic detection provides the closest thing to instrumental confirmation of a TLP
• Professional astronomers have been gradually discouraged from investigating TLPs — classified as Fortean phenomena and left largely to amateur observation — which means the instrumental record is less complete than it should be