Glossary term: 淩
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。
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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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木星、木衛一及其陰影，作者：Ralf Burkart，德國
Caption: 2021 年國際天文學聯合會 OAE 天體攝影比賽伽利略衛星類第一名。
這幅木星的延時攝影是於2017 年從德國拍攝的，作品精美地展示了伽利略衛星之一木衛一在木星前的凌星現象。由於這只是衛星在行星上投下影子，因此相當於從更遠的地方觀測地球上的月食。雖然衛星的影子從一開始就清晰可見，但在木星美麗的大氣帶背景下，第一次觀看視頻時可能很難發現衛星本身。反復觀看可以欣賞到這一奇妙的快速運動和旋轉過程。
Credit: Ralf Burkart/IAU OAE
License: CC-BY-4.0 Creative Commons 姓名標示 4.0 國際 (CC BY 4.0) icons
Venus Transit from Tempe, AZ, USA , June 5, 2012
Caption: While the planet Venus regularly passes between the Sun and the Earth, most of the time it passes above or below the Sun when observed from Earth. On rare occasions, the planet Venus passes directly in front of the Sun for observers on Earth. The last such Venus transits were in 2004 and 2012, respectively. The next such transit will be in 2117. The picture was taken at 18:54 PDT on June 5, 2012, from Tempe, Arizona, US. The telescope used was an 8" Schmidt-Cassegrain with ND5 filter; the camera was a Sony NEX5N with the APS sensor placed at prime focus. Clearly visible are the disk of the Sun, Venus as a prominent round spot. Several sun spots also appear on the solar disk.
Credit: Stephen Rector
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License: CC-BY-SA-3.0 Creative Commons Attribution-ShareAlike 3.0 Unported icons
Transit of Phobos from Mars
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Credit: NASA/JPL-Caltech/ASU/MSSS
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License: PD Public Domain icons
