その理由は次のとおりです。
* The Tropic of Capricorn is the circle of latitude that marks the southernmost point on Earth where the Sun can appear directly overhead at noon.
* December 21st 12月の至点であり、北半球で最も短い日光と南半球で最も長い日光時間がある日です。 On this day, the Sun reaches its southernmost declination.
Therefore, if the Sun passes through my zenith on December 21st, I must be situated on the Tropic of Capricorn.
