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This is Scientific American's 60-second Science, I'm Steve Mirsky.

这里是科学美国人——60秒科学系列，我是史蒂夫·米尔斯基。

Happy New Year! And if you've been away from work for a few days, you deserve some time off. Af???ter all, you've traveled far—even if you just stayed at home. According to NASA, just by being on the planet Earth in the last year, you've zipped about 584 million miles around the sun, at an average speed of about 67,000 miles per hour.

新年快乐！如果你远离了工作几天，那是你应得的休息。毕竟，你已经走了很远，即使你只是待在家里。根据美国国家航空航天局（简称NASA）的数据，仅仅只是待在地球上，去年一年你就已经围绕太阳移动了5.84亿英里，平均速度约为每小时6.7万英里。

(CLIP: Siren sound)

（音频剪辑：警笛声）

Hey, I wasn't speeding—in my inertial reference frame.

嘿，在我的惯性参考坐标系中，我可没有超速。

Of course, the trip was not a perfect circle. As Kepler showed, the Earth's orbit is an ellipse, with the sun at one of the two focal points. He also figured out the planet goes faster when it's at perihelion, nearer the sun, than when it's at aphelion¹, its furthest distance—which would explain why summer seems to zip by, except that the seasons are a function of the tilt² of the Earth's axis³, not its different distances from the sun. And the Earth rotated 365 and a quarter times during its sweep around the sun. The trip took 8,766 hours. Or 525,960 minutes. Or 31,557,600 seconds. Tick tock.

当然，你的路线并不是正圆。正如开普勒展示的那样，地球的公转轨道是一个椭圆，太阳位于椭圆的其中一个焦点上。他还发现，地球在靠近太阳的近日点时公转速度较快，而在离太阳最远的远日点时公转速度较慢。这可以解释为什么夏天似乎过得很快，还可以解释季节是地轴倾斜的产物，而不是由地球距离太阳的远近而形成的。地球绕太阳公转一圈的时间为365.25天。这趟旅行耗时8766个小时，或者说525960分钟，31557600秒。滴答。

For Scientific American's 60-second Science. I'm Steve Mirsky.

谢谢大家收听科学美国人——60秒科学。我是史蒂夫·米尔斯基。