Glossary term: 回歸線
Description: 回歸線是地球上的兩條緯線圈：北迴歸線（位於北緯23°26′11.2″）和南迴歸線（位於南緯23°26′11.2″）。
相對於其他恆星和其他天體，太陽在天空中的位置在一年中會發生變化，看起來會在黃道星座中移動。從春分日到秋分日，太陽位於北天球。在夏至日的當地正午左右，太陽直射北迴歸線。從秋分日到第二年的春分日，太陽位於南天球。在冬至日的當地正午左右，太陽直射南迴歸線。在春分日和秋分日當天，太陽直射赤道上空。
地球上兩條回歸線之間的區域通常被稱為“熱帶”。在熱帶地區，太陽每年有兩天在當地正午時分直射赤道。
赤道南北兩條回歸線的緯度即為地軸相對於地球繞太陽運轉的軌道的傾斜角度。
在西方，南北兩條回歸線分別以摩羯座和巨蟹座命名。這是因為在兩千年前的冬至日和夏至日，太陽看起來會分別經過這兩個星座。但由於地軸的進動，在如今的冬至日和夏至日，太陽不再出現在這兩個星座中。
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Term and definition status: The original definition of this term in English have been approved by a research astronomer and a teacher The translation of this term and its definition is still awaiting approval
This is an automated transliteration of the simplified Chinese translation of this term
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