1. Introduction
Solar activity has long shaped Earth’s environment, occasionally producing storms capable of altering the magnetic field and disturbing technological systems. During the first half of the twentieth century, the growing dependence on electricity, telecommunications, and advanced weaponry made human society more vulnerable to space weather effects (Usoskin et al. Reference Usoskin, Miyake, Baroni, Brehm, Dalla, Hayakawa, Hugh Hudson, Jull, Knipp, Koldobskiy, Maehara, Mekhaldi, Notsu, Poluianov, Rozanov, Shapiro, Spiegl, Sukhodolov, Uusitalo and Wacker2023). Revisiting that period reveals an intriguing question: could some unexplained wartime events have been influenced by the Sun?
This study reexamines major geomagnetic storms that occurred between 1938 and 1941, an interval corresponding to the early stages of World War II, to explore their possible connection with mysterious explosions and electrical failures reported around the globe. By combining historical documentation and current understanding of geomagnetically induced currents (GICs), we aim to shed light on how natural processes in space may have interacted with human technology under extreme conditions.
2. Historical Solar Activity and the 1941 Superstorm
Several intense geomagnetic storms punctuated the early years of World War II, notably those of January 1938, March 1940, November 1940, and September 1941. The September 1941 storm, however, was remarkable in both intensity and scope. It began with the emergence of an unusually large sunspot group, followed by a major solar flare that emitted strong ultraviolet and X-ray radiation. Within a day, a coronal mass ejection struck Earth, producing a global geomagnetic disturbance with six major impulses within 24 hours and a maximum K index of 9–a level rarely observed since (Cliver and Svalgaard Reference Cliver and Svalgaard2004; Hayakawa et al. Reference Hayakawa, Ebihara, Willis, Toriumi, Iju, Hattori, Wild, Oliveira, Ermolli and Ribeiro2019).
Reports from the time describe bright auroras across the northern hemisphere, visible as far south as New Mexico and North Africa. The storm caused radio blackouts, voltage fluctuations, and failures in long-distance communication systems. Coincidentally, numerous explosions were reported in munitions factories and industrial facilities in the United States, the United Kingdom, and Central Europe, with causes that remained unexplained or were attributed vaguely to “sabotage.” The simultaneity of these events with the geomagnetic peak invites consideration of an underlying solar connection.
3. Methodology and Archival Research
To explore these possible links, we analyzed international newspaper archives and institutional reports from 1938 to 1945. Sources included The New York Times, The Evening Star, Le Figaro, El Tiempo, and others accessible through the Library of Congress and the Bibliothèque nationale de France. Using search terms such as explosion, mysterious, sabotage, blackout, and aurora borealis, we identified multiple events of unclear origin that coincided temporally with geomagnetic storms.
One illustrative example occurred on November 12–13, 1940, when multiple U.S. powder plants exploded on the same day; Trojan Powder Company (New Jersey), Burton Powder Works (Pennsylvania), and a military depot near Atlantic City–during an active geomagnetic period. Earlier, during the January 1938 “Fatima Storm”, unexplained detonations were reported in France, Italy, and Java. The September 1941 storm produced another cluster of such events, particularly in North America and Europe, further reinforcing the temporal correlation.
4. Discussion and Implications
From a physical standpoint, large geomagnetic storms induce fluctuating electric fields on the ground that can drive currents through conductive networks, power lines, pipelines, and metallic structures. In modern times, similar effects have been linked to failures in rail signaling and power grids. During World War II, the same principle could have affected the electrical blasting circuits and detonators used in munitions plants, especially those relying on mercury fulminate or PETN, which are sensitive to electric discharge.
The 1941 storm’s magnetic fluctuations, recorded at observatories such as Kakioka (see Fig. 1) and Alibag, were sufficient to produce ground-level currents capable of generating millivolt potentials per meter, enough, in unshielded environments, to trigger electrical sparks. The simultaneity of factory explosions during that geomagnetic event provides circumstantial but compelling evidence for such a mechanism. Although alternative explanations such as industrial accidents or human error cannot be ruled out, the systematic clustering of unexplained detonations around strong space weather episodes points to a potentially underestimated influence of solar activity on wartime technologies.
Magnetic field data: Declination (D), Vertical (Z) and Horizontal (H) component, recorded by the Kakioka Geomagnetic Observatory in September 1941. The vertical lines mark dates where unexplained explosion events were identified in this research.
Figure 1 Long description
Three line graphs show geomagnetic data recorded by the Kakioka Geomagnetic Observatory in September 1941. Panel A: The line graph for Declination (D) has the vertical axis labeled 'D' and the horizontal axis labeled 'Day of the Month'. The graph shows fluctuations with a notable dip around the 17th day. Panel B: The line graph for the Vertical component (Z) has the vertical axis labeled 'Z (x10^4)' and the horizontal axis labeled 'Day of the Month'. This graph shows a significant drop around the 17th day. Panel C: The line graph for the Horizontal component (H) has the vertical axis labeled 'H (x10^4)' and the horizontal axis labeled 'Day of the Month'. This graph also shows a notable dip around the 17th day. Vertical lines mark specific dates where unexplained explosion events were identified.
The examination of archival and geophysical data reveals that intense solar storms, particularly the superstorm of September 1941, may have coincided with multiple unexplained explosions during the early years of World War II, as shown in Fig. 1. While a definitive causal link remains speculative, the preliminary historical and physical evidence support the hypothesis that geomagnetic disturbances could have interacted with sensitive electrical and explosive systems.
Beyond its historical implications, this study reminds us that solar activity continues to pose a risk to modern infrastructures that are dependent on electricity, communication, and navigation. The lessons drawn from this period underscore the importance of continuous solar monitoring, interdisciplinary research, and predictive modeling to enhance the resilience of technological systems against extreme space weather.
Acknowledgements
The research was sponsored by the DynaSun project and has thus received funding under the Horizon Europe programme of the European Union under grant agreement (no. 101131534). Views and opinions expressed are however those of the author(s) only and do not necessarily reflect those of the European Union and therefore the European Union cannot be held responsible for them.
