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.
那是北面的北回归线 以及南面的南回归线， 这些是我知道的。 但我很惊讶的学到了这一小个事实： 这些不是制图者的线， 像纬度或国家的边界， 它们代表着地球倾斜造成的天文现象， 而它们一直在改变。