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Glossary term: 昼夜平分点

Description: 昼夜平分点(春分和秋分)是太阳在其年度黄道运行中穿越天球赤道的时刻。该词源自拉丁语“aequinoctium”,其中“aequus”意为“相等”,“nox”(属格形式为“noctis”)意为“夜晚”。在昼夜平分点这一天,不仅仅是接近赤道的区域,全球的昼夜长度大致相等。对于地球上的观察者,太阳在这一天从正东方升起,沿着天球赤道的路径运行,最后在正西方落下。每年有两次昼夜平分点,春分大约在3月20日,秋分在9月23日。在3月的春分,太阳看起来开始向北半球移动;而在9月的秋分,太阳看起来则向南半球移动。

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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

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".

Related Media


12 幅日落图片。日落从顶部的左侧移动到中部的右侧,再回到底部的左侧

每月日落的地方

Caption: 这组图片是在菲律宾布拉干省的圣拉斐尔用智能手机拍摄的,它捕捉到了地球轴向倾斜和环绕太阳运行所导致的日落位置在一年中的变化。从 2022 年 1 月到 12 月,每张图片都反映了黄昏时分背景和太阳位置的变化。在十月,可以观察到树叶的变化和一根电线杆的出现。这组作品是地球与太阳之间的天体舞蹈以及地面自然景观变化的视觉见证。
Credit: John Paul Pile/IAU OAE (CC BY 4.0)

License: CC-BY-4.0 Creative Commons 署名 4.0 国际 (CC BY 4.0) icons


明亮的曲线从左侧上升,在右侧达到顶峰。线条越往左,峰值越高。

太阳的轨迹

Caption: 这幅令人陶醉的图片于 2018 年 6 月 21 日至 2018 年 12 月 21 日期间在德国拍摄,是艺术与科学的诗意融合,展现了大自然的韵律和时间的流逝。它合并了六个月内每天不同时间段拍摄的图片。每条曲线都追踪了太阳在特定一天内穿越天空的路径(或弧线)。在这里,太阳划过的弧线被投影扭曲,使其看起来像一条曲线。每天划过天空的弧线位置随着太阳在天空中的季节性移动而变化。这幅图片是用一个咖啡罐制成的简易针孔摄像机拍摄的,它展示了太阳在六个月时间里的旅程,以及日弧从夏季较高(太阳在天空中的位置较高)逐渐移动到冬至最低位置的过程。太阳路径上的间隙代表太阳被云层遮挡的日子或时段。这幅图片生动地表现了四季的变化,展示了太阳在天空中随着白天变短或变长而舞动的轨迹。
Credit: Frank Niessen/IAU OAE (CC BY 4.0)

License: CC-BY-4.0 Creative Commons 署名 4.0 国际 (CC BY 4.0) icons


三组太阳在天空中的运动轨迹。最高的轨迹几乎穿过图像的中央,而最低的轨迹位于图像高度的六分之一处。

日至和日分

Caption: 这张引人入胜的照片记录了在2007年12月21日至2008年6月20日期间,太阳在土耳其布尔萨的冬至(下)、春分(中)以及夏至(上)在天空中运动的轨迹。摄影师使用鱼眼镜头,在这三天中以固定的时间间隔拍摄太阳从日出到日落的位置,生动展示了一年中昼夜长短的变化。太阳每日在天空中的运行轨迹、正午高度、日出和日落的位置,以及白昼的长度,均由地球自转轴与其绕太阳轨道的倾斜角度决定。这一系列照片拍摄于布尔萨的一座屋顶,当地的地形偶尔会遮挡地平线,为画面增添了独特的地域特征。照片中的方向以北朝上、以南朝下,这组视觉日记成为中北纬地区居民欣赏太阳运行轨迹变化的精彩呈现。
Credit: 通奇·特泽尔/国际天文学联合会教育办公室 (CC BY 4.0)

License: CC-BY-4.0 Creative Commons 署名 4.0 国际 (CC BY 4.0) icons


许多日落的图像拼接在一起。太阳的落下位置从冬天的左侧变化到夏天的右侧。

西落幅度

Caption: 这张合成照片拍摄于意大利西西里岛的 Gatto Corvino 村,展示了从2016年到2017年冬至到夏至期间,太阳在海面上不同位置的落日景象。中心框为正西方。随着地球绕太阳公转,太阳的落下(和升起)位置从夏季的正西(东)方向偏北,变化到冬季的正西(东)方向偏南。在春分和秋分时,白昼和黑夜的长度相等,太阳从正东方升起,正西方落下。太阳在地平线上位置的变化是由于地球绕太阳运行时的自转轴倾斜。在地球的温带地区,夏至和冬至时,正午太阳在地平线上的高度角分别达到最高和最低值。
Credit: Marcella Giulia Pace/IAU OAE (CC BY 4.0)

License: CC-BY-4.0 Creative Commons 署名 4.0 国际 (CC BY 4.0) icons

Related Diagrams


Pisces appears as a SW-pointing v-shape with loops at the end of each line. The ecliptic runs WSW to ENE through Pisces.

Pisces Constellation Map

Caption: The constellation Pisces along with its bright stars and surrounding constellations. Pisces is surrounded by (going clockwise from the top) Andromeda, Pegasus, Aquarius, Cetus, Aries and Triangulum. Pisces lies on the ecliptic (shown here as a blue line), this is the path the Sun appears to take across the sky over the course of a year. The Sun is in Pisces from mid March to mid April. Thus the Sun is in Pisces at the March equinox. At this point the ecliptic crosses the celestial equator. The Sun’s location at the spring equinox is used to set the zero point of the Right Ascension positional coordinate. The other planets of the Solar System can often be found in Pisces. Pisces spans the celestial equator and is thus visible at some time in the year from all of planet Earth. In the most arctic or antarctic regions of the world, some parts of the constellation may not be visible. Pisces is most visible in the evenings in the northern hemisphere autumn and southern hemisphere spring The grand design spiral galaxy M74 is marked on this diagram with a small red circle. The y-axis of this diagram is in degrees of declination and with north as up and the x-axis is in hours of right ascension with east to the left. The sizes of the stars marked here relate to the star's apparent magnitude, a measure of its apparent brightness. The larger dots represent brighter stars. The Greek letters mark the brightest stars in the constellation. These are ranked by brightness with the brightest star being labeled alpha, the second brightest beta, etc., although this ordering is not always followed exactly. The dotted boundary lines mark the IAU's boundaries of the constellations and the solid green lines mark one of the common forms used to represent the figures of the constellations. Neither the constellation boundaries, nor the lines joining the stars appear on the sky.
Credit: Adapted by the IAU Office of Astronomy for Education from the original by IAU/Sky & Telescope

License: CC-BY-4.0 Creative Commons 署名 4.0 国际 (CC BY 4.0) icons