A Transient Lunar Phenomenon (TLP), as described by American astronomer Winifred Cameron, is a change in the appearance of the moon’s surface, such as a bright flash in a specific region, the presence of gases or mists, or the appearance of coloration (typically red, blue, or green) (3). Such an event can be as short in duration as a few minutes or as long as a few days (Herschel 229). Notable examples were recorded as long ago as the 6th century (Cameron 3). These phenomena present a peculiar mystery as our moon is typically thought to be geologically dead, with no internal heat, gas exchange, or notable atmospheric conditions (Dickson). In fact, during the landing of Apollo 11, NASA asked Neil Armstrong to observe an area that commonly experiences TLP. Armstrong noted that the crater, named Aristarchus after a Greek astronomer who often observed the moon’s surface, was “considerably more illuminated than the surrounding area,” but could see no clear explanation for its fluorescence (Time).
Though observations of TLP have been recorded for hundreds of years, scientists have been unable to offer a concrete explanation for TLP such as those described by British astronomer Sir William Herschel as “a point of light, resembling a star of the nth magnitude; having a reddish cast.” Theories have ranged from divine influence to solar flare to meteorite impacts. A common theory is that the 11-year solar cycle often creates sunspots and other reflections that we perceive as changes in the moon’s surface (Rundle). However, Jill Scrambler of the British Astronomical Association may have debunked this theory and shed further light on the lunar mystery. Her 2013 report overlaid observations of these phenomena with documented solar cycle data all the way back to 1700. Refuting the sunspot hypothesis, she found no correlation between the solar cycle and recorded TLP events. Though unable to offer a definitive explanation, Scrambler’s article suggests that, given the nature of what has been observed, there are only a few possibilities for the cause of TLP (Scrambler 18). Meteorite impacts, plasma tails left by the Earth’s orbit, or even underground gas-filled caverns in the moon are cited as the most likely culprits (Rundle). Magnetic anomalies in the moon, such as those extensively studied by former Harvard Professor of Earth and Planetary Sciences Dr. Sarah Stewart, serve as another possible explanation for TLP (Zito 420).
Theories have ranged from divine influence to solar flare to meteorite impacts.”
In an April 2014 article on NASA’s web site, Rick Elphic details the organization’s efforts to explain the origins of TLP. He writes that in 2013, NASA’s Lunar Atmosphere and Dust Environment Explorer (LADEE) spacecraft was launched to gather data and make observations of the most active TLP sites on the moon, among other scientific goals. After orbiting the moon at low altitude for a hundred days, LADEE was deliberately crashed into the moon’s surface as a method of stirring up lunar dust for further experiments and examination. On April 17th of this year, scientists received the final data recorded by LADEE and are still in the analysis process. LADEE detected lunar dust in the moon’s atmosphere, which NASA scientists suspect could be the cause for some of the TLP observed from Earth. Further analysis of the moon’s surface and trapped gases will likely provide further insights.
With the incredible array of telescopes, spacecraft, and trained observers examining the night sky, it seems likely that we will soon put an end to this ancient mystery. No longer the irreproducible tale of a single observer here or there, Transient Lunar Phenomena today capture the attention of dozens of trained scientists whenever they occur. For now, though, we ponder a flash of light or a change in hue just as Aristarchus, Sir William Herschel, and others have ever since we began to look up at the stars.
- “A Giant Leap for Mankind.” Time 25 July 1969.
- Cameron, Winifred S. “Analyses of Lunar Transient Phenomena (LTP) Observation from 557- 1994”, National Space Science Data Center, 1994.
- Dickson, David. “Mysterious Moon Flashes: Could the Transient Lunar Phenomena Be Linked to the Solar Cycle?” Universe Today. Universe Today, 14 Apr. 2013. Web. 10 July 2014.
- Rundle, Michael. “Transient Lunar Phenomena: Mysterious ‘Moon Flashes’ Explained? British Astronomical Association Study Discounts Sunspot Theory.” Huffington Post Tech. Huffington Post, 15 Apr. 2013. Web. 10 June 2014.
- Elphic, Rick. “LADEE Project Scientist Update: The Legacy Lives On!” NASA. NASA, 22 Apr. 2014.
- Herschel, William. “An Account of Three Volcanoes on the Moon.” Philosophical Transactions of the Royal Society of London, Vol. LXXVII, 229-232 (1787): 229. Archive.
- Scrambler, Jill. “Comparison of Transient Lunar Phenomena with the Solar Cycle.” British Astronomical Association Lunar Section Circular 50.3 (2013): 14-18. British Astronomical Association, Mar. 2013.
- Zito, Richard. “A New Mechanism for Lunar Transient Phenomena.” Icarus 82.2 (1989): 419-22.
Jackson Allen is a Brevia staff writer. He can be reached at firstname.lastname@example.org.