Glossary term: 近日點
Description: 太陽系中的大多數天體都是橢圓軌道，太陽位於其中一個焦點。近日點是軌道上天體距離太陽最近的點。從數學上來說，該點標誌著橢圓長軸的一端。其中 "peri" 表示最近點， "helion" 表示太陽。因此，只有當中心體是太陽時纔可以使用這個詞。當中心天體是一顆非太陽恆星時，術語為 "periastron" ；當繞行的中心體是地球時，術語為 "perigee" 。無論中心天體是什麼，通用的術語是 "periapsis" 。
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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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In Other Languages
- 阿拉伯語: الحضيض الشمسي
- 德語: Perihel
- 英語: Perihelion
- 法語: Périhélie
- 義大利語: Perielio
- 日語: 近日点 (external link)
- 韓語: 근일점
- 簡體中文: 近日点
Related Media
Halley's Comet
Caption: Halley’s Comet, is a well-known periodic comet, named after the English astronomer Edmond Halley. It has an orbital period of approximately 75 years and is visible from Earth with the naked eye when it passes through the inner solar system.
The image shows Halley’s Comet, officially designated 1P/Halley, with a tail of gas and dust streaming away from the Sun. It was taken from the La-Silla-Observatory in Chile in 1986 during Halley's Comet's last visit to the inner solar system. The stars in this image appear elongated or as lines of three different colored dots as image was created from three separate observations in different colors of light and the telescope was tracking the comet, which was moving very slightly compared to the background stars. Note that the comets tail does not point in exactly the same direction as the elongation of the stars. This shows us that the comet tail is not always behind the comet, but instead pointing away from the Sun.
The comet passes its perihelion (closest distance to the Sun) at a distance of around 0.59 astronomical units, right between the orbits of Mercury and Venus. Beyond Neptune, it reaches its aphelion (furthest distance from the Sun) at a distance of approximately 35 astronomical units. Halley's Comet reached aphelion in December 2023 and is now moving inwards again. It is expected to be seen with the naked eye from Earth again in mid-2061.
Credit: ESO
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