Definition of "spring equinox" []

• Vernal equinox (noun)

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• "The need for this intercalation was, at the time of Christ, still determined empirically, in such a way that the celebration of the Pasch at the full moon or fourteenth day of the first month, Nisan, should always occur after the spring equinox (Mar. 21st)."
• "This happens twice a year, and the times when the sun passes the equator are called the vernal or spring equinox and the autumnal equinox respectively."