北回归线是地球上北纬23度26分21秒的纬度圈,是太阳天顶位置每年于夏至日从赤道回归北半球,阳光垂直照射地球北纬的极限界线。同时,也是天文、地理上划分热带和北温带的依据。北回归线共穿越十六个国家和地区,在我国穿越台、粤、桂、滇四省,汕头也恰是北回 The Tropic of Cancer is a latitude circle of 23 degrees 26 minutes and 21 seconds north latitude on the earth. It is the limit of the sun’s zenith position that returns from the equator to the northern hemisphere every summer solstice and the sun shines perpendicular to the northern latitude of the earth. At the same time, it is also the basis for the astronomical and geographical division of tropical and northern temperate zones. The Tropic of Cancer passes through 16 countries and regions. It crosses Taiwan, Guangdong, Guangxi, and Hebei provinces, and Shantou is also the North