Now that's the Tropic of Cancer in the north and the Tropic of Capricorn in the south, that much I knew, but I was surprised to learn this little fact: Those are not cartographers' lines, like latitude or the borders between nations, they are astronomical phenomena caused by the Earth's tilt, and they change.
北端が北回帰線で 南端が南回帰線だぐらいしか 南端が南回帰線だぐらいしか 知らなかった私が 驚いたのは 回帰線が 緯度や ー 国境といった 製図上の線でなくて 地球の傾きで決まっていて さらには年々変化して