词条凌

描述: 当一个天体穿过另一个角大小较大的天体和观测者之间时，就发生了凌星。从观测者的角度看，遮挡天体移动到被遮挡天体的前面，阻挡了被遮挡天体表面的一部分视线。如果从观测者和被遮挡天体之间经过的遮挡天体的角大小大于后者，这种情况被称为掩星，而不是凌星。对于同一系统，被一个观测者看到的凌星现象，可能不会被另一个来自不同角度的观测者看到。

在太阳系中，从地球上看水星和金星有时都会凌日。从地球上看，绕太阳系行星运行的卫星经常会穿过其所绕转行星的表面。

环绕其他恒星运行的行星（系外行星）通常是在凌星时被发现的，它们会遮挡住恒星的部分光线，从观测者所在位置看去，恒星会显得略微暗淡。只有当行星的轨道平面与地球的视线相交时，从地球上看绕恒星运行的行星才会凌星。因此，用凌星法寻找行星只能探测到银河系中的一小部分行星。凌星还可以用来估计系外行星的大小。

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The OAE Multilingual Glossary is a project of the IAU Office of Astronomy for Education (OAE) in collaboration with the IAU Office of Astronomy Outreach (OAO). The terms and definitions were chosen, written and reviewed by a collective effort from the OAE, the OAE Centers and Nodes, the OAE National Astronomy Education Coordinators (NAECs) and other volunteers. You can find a full list of credits here. All glossary terms and their definitions are released under a Creative Commons CC BY-4.0 license and should be credited to "IAU OAE".

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其他语言版本

阿拉伯语: العبور
德语: Transit
英语: Transit
法语: Transit
意大利语: Il transito
繁体中文: 淩

相关媒体

木星、木卫一及其阴影，作者：Ralf Burkart，德国

图注： 2021 年国际天文学联合会 OAE 天体摄影比赛伽利略卫星类第一名。这幅木星的延时摄影是于2017 年从德国拍摄的，作品精美地展示了伽利略卫星之一木卫一在木星前的凌星现象。由于这只是卫星在行星上投下影子，因此相当于从更远的地方观测地球上的月食。虽然卫星的影子从一开始就清晰可见，但在木星美丽的大气带背景下，第一次观看视频时可能很难发现卫星本身。反复观看可以欣赏到这一奇妙的快速运动和旋转过程。
来源： Ralf Burkart/IAU OAE

License: CC-BY-4.0 知识共享许可协议署名 4.0 国际 (CC BY 4.0) 图标

A black background with a white disk. On the disk is a prominent much smaller black disk & less prominent tiny dark smudges

Venus Transit from Tempe, AZ, USA , June 5, 2012

图注： 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.
来源： Stephen Rector 来源链接

License: CC-BY-SA-3.0 知识共享许可协议 Attribution-ShareAlike 3.0 Unported 图标

The dark, irregular shape of Phobos crosses the lower portion of the Sun’s disk, obscuring roughly one quarter of it.

Transit of Phobos from Mars

图注： This video shows the Sun viewed from Mars as Mars’ moon Phobos transits across the solar disk. This video is composed of images taken from the Martian surface on the 30th of September 2024 by the Mastcam-Z camera of NASA’s Perseverance Mars rover. While our Moon is perfectly sized to eclipse the Sun when seen from the Earth’s surface, Phobos’s size and orbit mean that it cannot cover the solar disk completely. This means that this event is a transit and not an eclipse. This video is in real time, with the entire transit lasting just 32 seconds. This compares with the several hours a solar eclipse on Earth takes from the Moon first obscuring part of the Sun to the Sun being completely visible again. This is due to Phobos’ much shorter orbital period of just over seven and a half hours compared to the Moon’s orbital period of 27 days as well as the solar disk appearing slightly smaller from Mars than it does from Earth. Note the non-spherical shape of Phobos as it crosses the solar disk.
来源： NASA/JPL-Caltech/ASU/MSSS 来源链接

License: PD 公共领域图标