2025年9月14日
Planets of the Solar System: Tilts and Spins
Video Credit: NASA, Animation: James O’Donoghue (U. Reading)
Explanation: How does your favorite planet spin? Does it spin rapidly around a nearly vertical axis, or horizontally, or backwards? The featured video animates NASA images of all eight planets in our Solar System to show them spinning side-by-side for an easy comparison. In the time-lapse video, a day on Earth — one Earth rotation — takes just a few seconds. Jupiter rotates the fastest, while Venus spins not only the slowest (can you see it?), but backwards. The inner rocky planets across the top underwent dramatic spin-altering collisions during the early days of the Solar System. Why planets spin and tilt as they do remains a topic of research with much insight gained from modern computer modeling and the recent discovery and analysis of hundreds of exoplanets: planets orbiting other stars.
Tomorrow’s picture: sun belch
太阳系行星: 倾斜与自转
影像提供: NASA, Animation: James O’Donoghue (U. Reading)
说明: 你最喜爱的行星是如何自转的呢？它是绕着一条几乎垂直的轴快速自转，还是水平自转，甚至是逆向自转？这段主题影片将NASA的八大行星在我们的太阳系的影像进行动画处理，并将它们并列呈现自转状态，方便比较。在缩时影片片中，地球的一天（即一次自转）仅需数秒即可完成。在所有行星之中，木星的自转速度最快，而金星不仅自转最慢（你能看出来吗？），甚至还是逆向自转。影片上方的类地行星（内侧岩质行星）在太阳系早期都曾经历剧烈的碰撞事件，显著改变了它们的自转方式。至于为何行星会呈现目前的自转与倾角，仍是持续研究的主题。现代电脑模拟与数百颗系外行星（环绕其他恒星的行星）的发现与分析，正为这一问题提供了许多新的见解。
明日的图片: sun belch
