Description: 當一個天體穿過另一個角大小較大的天體和觀測者之間時，就發生了凌星。從觀測者的角度看，遮擋天體移動到被遮擋天體的前面，阻擋了被遮擋天體表面的一部分視線。如果從觀測者和被遮擋天體之間經過的遮擋天體的角大小大於後者，這種情況被稱為掩星，而不是凌星。對於同一系統，被一個觀測者看到的凌星現象，可能不會被另一個來自不同角度的觀測者看到。

在太陽系中，從地球上看水星和金星有時都會凌日。從地球上看，繞太陽系行星運行的衛星經常會穿過其所繞轉行星的表面。

環繞其他恆星運行的行星（系外行星）通常是在凌星時被髮現的，它們會遮擋住恆星的部分光線，從觀測者所在位置看去，恆星會顯得略微暗淡。只有當行星的軌道平面與地球的視線相交時，從地球上看繞恆星運行的行星才會凌星。因此，用凌星法尋找行星只能探測到銀河系中的一小部分行星。凌星還可以用來估計系外行星的大小。

Related Terms:

• 日蝕
• 橢圓
• 系外行星
• 光變曲線
• 測光
• 掩星

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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