近日点的太阳

2025年1月4日

Welcome to Perihelion
Image Credit & Copyright: Peter Ward (Barden Ridge Observatory)

Explanation: Earth’s orbit around the Sun is not a circle, it’s an ellipse. The point along its elliptical orbit where our fair planet is closest to the Sun is called perihelion. This year perihelion is today, January 4, at 13:28 UTC, with the Earth about 147 million kilometers from the Sun. For comparison, at aphelion on last July 3 Earth was at its farthest distance from the Sun, some 152 million kilometers away. But distance from the Sun doesn’t determine Earth’s seasons. It’s only by coincidence that the beginning of southern summer (northern winter) on the December solstice – when this H-alpha picture of the active Sun was taken – is within 14 days of Earth’s perihelion date. And it’s only by coincidence that Earth’s perihelion date is within 11 days of the historic perihelion of NASA’s Parker Solar Probe. Launched in 2018, the Parker Solar Probe flew within 6.2 million kilometers of the Sun’s surface on 2024 December 24, breaking its own record for closest perihelion for a spacecraft from planet Earth.

Tomorrow’s picture: rocket launch

近日点的太阳
影像提供与版权: Peter Ward (Barden Ridge Observatory)

说明: 地球绕行太阳的轨道并非圆形，而是椭圆。地球在椭圆轨道上最靠近太阳的点称为近日点。今年的近日点会出现在世界时1月4日13:28 UTC，届时地球距离太阳约1亿4千7百万公里远。作为对照，去年在7月3日的远日点时，地球与太阳相去约1亿5千2百万公里（相差5百万公里）。 想当然耳，与太阳的距离并非地球季节发生变化的原因。上面这幅摄于去年冬至的活跃期太阳氢α滤镜影像，取像时与地球运行到近日点相隔不到14天。而美国国家航空航天局帕克太阳探测器的历史性掠日，则是比近日点要早11天。发射于2018年的帕克太阳探测器，在2024年12月24日那天，以不至6.2百万公里的距离掠过太阳表面，打破它自己先前创下的地球航天器近日记录。

明日的图片: rocket launch