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| A cover commemorating the official beginning of the International Geophysical Year (1957), postmarked in Moscow with a hand cancel on July 1, 1957. |
The International Geophysical Year was a global scientific initiative that spanned from July 1, 1957, to December 31, 1958. It focused on eleven branches of Earth sciences, including aurora and airglow, cosmic rays, geomagnetism, gravity, ionospheric physics, precise longitude and latitude measurements (mapping), meteorology, oceanography, seismology, and solar activity.
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| A rocket mail from the Rocket Research Institute, launched on rocket number 3, postmarked at Topaz with a hand cancel on July 1, 1957. This date marks the start of the International Geophysical Year. |
Both the Soviet Union and the U.S. launched artificial satellites for this event; the Soviet Union's Sputnik 1, which was successfully launched on October 4, 1957, became the world's first artificial satellite. Other notable accomplishments of the IGY included the discovery of the Van Allen radiation belts by Explorer 1, launched on January 31, 1958, and the mapping of mid-ocean submarine ridges, which provided significant support for plate tectonic theory. Additionally, the rare occurrence of hard solar corpuscular radiation, which poses a serious risk for manned space flight, was also detected.
(Reference from
International Geophysical Year)
