International Quiet Sun Year
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International Quiet Sun Year[¦in·tər¦nash·ən·əl ¦kwī·ət ′sən ‚yir]
An international cooperative effort, similar to the International Geophysical Year and extending through 1964 and 1965, to study the sun and its terrestrial and planetary effects during the minimum of the 11-year cycle of solar activity. Abbreviated IQSY. Also known as the International Year of the Quiet Sun.