Astronomy Picture of the Day——太阳系的行星：倾斜与自转
Planets of the Solar System: Tilts andSpins
Video Credit: NASA, Animation: JamesO'Donoghue (JAXA)
Explanation: How does your favorite planetspin? Does it spin rapidly around a nearly vertical axis, or horizontally, orbackwards? The featured video animates NASA images of all eight planets in ourSolar System to show them spinning side-by-side for an easy comparison. In thetime-lapse video, a day on Earth -- one Earth rotation -- takes just a fewseconds. Jupiter rotates the fastest, while Venus spins not only the slowest(can you see it?), but backwards. The inner rocky planets, across the top, mostcertainly underwent dramatic spin-altering collisions during the early days ofthe Solar System. The reasons why planets spin and tilt as they do remains a topicof research with much insight gained from modern computer modeling and therecent discovery and analysis of hundreds of exoplanets: planets orbiting otherstars.
太阳系的行星：倾斜与自转
你直到你最喜欢的太阳系行星是如何自转的吗？它是围绕着近乎垂直的轴快速旋转，还是水平旋转，亦或是向后旋转？这段精彩视频由NASA拍摄，它生动地呈现了太阳系八大行星，将它们并排旋转以便于比较。在这段延时视频中，地球上的一天即地球自转一圈，只需要几秒钟。木星的自转速度最快，而金星的自转速度不仅最慢（你能看出它在动吗？），而且还向后旋转。在太阳系的早期，系内岩石行星（视频上部）肯定经历了剧烈的自转改变碰撞。行星自转和倾斜的原因仍然是一个研究课题，我们从计算机模拟和最近对数百颗系外行星的发现和分析中获得了许多见解。
参考文献：
https://youtu.be/my1euFQHH-o
近期文章：
Astronomy Picture of the Day——“磁”猎户