The three-day May 1921 geomagnetic storm, also known as the New York Railroad Storm, was caused by the impact of an extraordinarily powerful
coronal mass ejection on
Earth's
magnetosphere
In astronomy and planetary science, a magnetosphere is a region of space surrounding an astronomical object in which charged particles are affected by that object's magnetic field. It is created by a celestial body with an active interior dynam ...
. It occurred on 13–15 May as part of
solar cycle 15, and was the most intense geomagnetic storm of the 20th century.
Since it occurred before the extensive interconnectivity of electrical systems and the general electrical dependence of infrastructure in the developed world, its effect was restricted; however, its ground currents were up to an order of magnitude greater than those of the
March 1989 geomagnetic storm which interrupted electrical service to large parts of northeastern North America.
Effects
The storm's electrical current sparked a number of fires worldwide, including one near
Grand Central Terminal
Grand Central Terminal (GCT; also referred to as Grand Central Station or simply as Grand Central) is a commuter rail terminal located at 42nd Street and Park Avenue in Midtown Manhattan, New York City. Grand Central is the southern terminus ...
which made it known as the "New York Railroad Storm".
Contemporary scientists estimated the size of the
sunspot
Sunspots are phenomena on the Sun's photosphere that appear as temporary spots that are darker than the surrounding areas. They are regions of reduced surface temperature caused by concentrations of magnetic flux that inhibit convection. Sun ...
(AR1842)
which began on May 10th—and caused the storm—as .
The storm was extensively reported in
New York City, which was a center of telegraph activity as a railroad hub.
Auroras ("northern lights") appeared throughout the eastern
United States, creating brightly-lit night skies.
Telegraph service in the U.S. first slowed and then virtually stopped at about midnight on 14 May due to blown fuses and damaged equipment. Radio propagation was enhanced during the storm due to ionosphere involvement, however, enabling unusually good long-distance reception. Electric lights were not noticeably affected.
Undersea telegraph cables were affected by the storm. Damage to telegraph systems was also reported in Europe
and the
Southern Hemisphere.
2021 study estimated
Dstm of -533 nT.
See also
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Active region
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Geomagnetic storm
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List of solar storms
References
Footnotes
Bibliography
*The Aurora Borealis of May 14, 1921
* A bibliography of newspaper and journal articles.
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External links
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{{Solar storms
1921 in science
1921 natural disasters
Geomagnetic storms
1921 natural disasters in the United States
May 1921 events