季节

天文·每日一图

土星的春分

The planet Saturn is pictured 6 times in a horizonal column, labelled by years with 2020 at the top and 2025 at the bottom. As the years progress, Saturn’s ring appear less prominent. Please see the explanation for more detailed information.
这张图以水平列方式展示了土星在六个不同年份的影像,从上到下依次标注为2020年至2025年。随着年份推移,土星的光环逐渐变得不那么显眼。有关更多详细信息,请参阅说明。

天文·每日一图

土星环消失之谜

The planet Saturn is shown many times down the composite image. The top image was taken in 2020 and shows Saturn’s rings very clearly, whereas the bottom image was taken in 2025 and the rings are only visible as a dark line across the planet. The six images show the progression year by year. Please see the explanation for more detailed information.
土星在合成图像中多次出现。上方图像拍摄于2020年,清晰地展现了土星环;下方图像拍摄于2025年,土星环仅以一条暗线的形式横跨整个土星。这六幅图像展现了土星环逐年变化的轨迹。有关更多详细信息,请参阅说明。

天文·每日一图

土星的一季

2023年8月25日 A Season of Saturn Image Credit & Copyright: Andy Casely Explanation: Ringed planet Saturn will be at its 2023 opposition, opposite the Sun in Earth’s skies, on August 27. While that puts the sixth planet from the Sun at its brightest and well-placed for viewing, its beautiful

天文·每日一图

秋分: 卡拉尼什巨石阵上空的日行迹

2022年9月18日 Analemma over the Callanish Stones Image Credit & Copyright: Giuseppe Petricca Explanation: If you went outside at the same time every day and took a picture that included the Sun, how would the Sun’s position change? A more visual answer to that question is an analemma, a comp

天文·每日一图

土星环与土星的季节

2021年9月19日 Rings and Seasons of Saturn Image Credit & Copyright: Damian Peach/SEN Explanation: On Saturn, the rings tell you the season. On Earth, Wednesday marks an equinox, the time when the Earth’s equator tilts directly toward the Sun. Since Saturn’s grand rings orbit along the

天文·每日一图

近日点与远日点

2021年7月8日 Perihelion to Aphelion Image Credit & Copyright: Richard Jaworski Explanation: Aphelion for 2021 occurred on July 5th. That’s the point in Earth’s elliptical orbit when it is farthest from the Sun. Of course, the distance from the Sun doesn’t determine the seasons. T

科普

行星上的季节变化

Credit:NASA 9月22日是北半球的秋分,同时也是南半球的春分,也就是说昨天是北半球入秋第一天,南半球入春第一天。 地球上有着明显的春夏秋冬,四季分明,但不是太阳系中每颗行星都有明显的四季变化。 Credit:NASA 行星上的季节变化由两个因素引起,轴倾角(axial tilt)和轨道偏心率(orbital eccentricity)。轴倾角指的是行星的自转轴相对于轨道面的倾斜程度。水星,金星和木星的轴倾角很小,地球,火星,土星,海王星的轴倾角都是二十多度,而天王星最夸张,轴倾角82度,和其他行星兄弟相比,几乎是躺着。 轨道偏心率简单说指的是远日点和近日点的变化比,太阳系所有的行星的

天文·每日一图

近日点与远日点的太阳

2020 January 9 Perihelion to Aphelion Image Credit & Copyright: Ian Griffin (Otago Museum) Explanation: Perihelion for 2020, the point in Earth’s elliptical orbit when it is closest to the Sun, occurred on January 5th. The distance from the Sun doesn’t determine the seasons, though.

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