Strange Flashes of Light Seen on the Moon — What are They?

Transient Lunar Phenomena (TLP) have been seen for centuries, and have been carefully examined by researchers since the 1950’s. As long as 1,000 years ago, lunar observers reported flashes of light on the Moon lasting from minutes to hours before fading away. Oddly, astronomers have little idea of the cause of this phenomenon on our nearest neighbor. These events, which often light up small regions of the Moon in red or violet light, take place several times a week. The effect can cover areas up to 100 kilometers (63 miles) from side to side.

Meteors striking the Moon can result in brief flashes of light, but many TLP events last for hours. Electrically-charged particles from the solar wind striking the lunar surface could also result in flashes of light, but events of this nature would fade quickly, unlike many of the TLP events recorded throughout history. Another possible cause of these events could involve movements of the lunar surface.

“Seismic activities were also observed on the moon. When the surface moves, gases that reflect sunlight could escape from the interior of the moon. This would explain the luminous phenomena, some of which last for hours,” said Hakan Kayal, Professor of Space Technology at Julius-Maximilians-Universität Würzburg (JMU) in Bavaria, Germany.

Some of these events are marked by periods of darkness, rather than a flash of light, suggesting an unknown process is at work on our planetary companion.

A TLP event recorded on the Moon, seen as the white dot near the center of the photo. Image credit: Columbia University.

A New Way of Looking at Things

Kayal’s team assembled a telescope specifically designed to search for TLP events as they occur. Located 100 kilometers (63 miles) north of Seville, Spain, this instrument consists of a pair of telescopes, keeping a constant eye on our planetary neighbor. When a flash of light is spotted through each telescope, the remotely-controlled system records photographs and videos of the event, and emails researchers.

The skills learned in the construction and operation of this telescope may be applied to future missions launched into space, where atmospheric events will not register false alarms.

The European Space Agency (ESA) keeps a constant watch on the Moon, and any event seen by the new telescope in Spain is checked against their observations. Only if a potential TLP is seen by both groups is the event confirmed.

It’s a Bird… It’s a Plane…

“And he beholds the moon; like a rounded fragment of ice filled with motionless light.” ― Gustave Flaubert, The Temptation of St. Antony

The Aristarchus Plateau, stretching 43 kilometers (27 miles) across, is known to be a hot spot of Transient Lunar Phenomena events. This region is seen in the upper part of this photo. Image credit: NASA

Kayal is refining the software which runs the telescope, utilizing artificial intelligence to distinguish TLP events from passing airplanes and birds passing through the field of view. He estimates it will take a year for updates to be complete.

As the United States, China, and private industries race to place humans on the Moon, it is vital to understand how these events are formed, in order to determine if they may affect human missions to the lunar surface.

“Anyone who wants to build a lunar base at some point must of course be familiar with the local conditions,” Kayal explains.

Even close to our own world, mysteries remain unsolved. But, with this new telescope and teams of researchers working on understanding the nature of these events, astronomers may soon have an answer to this lunar enigma.

The Cosmic Companion

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James Maynard is the author of two books, and thousands of articles about space and science. E-mail:

The Cosmic Companion

Exploring the wonders of the Cosmos, one mystery at a time