評論
打印
Yael, do you notice the days changing length over the course of the year?
雅埃爾，你有沒有注意到一年中每一天的長度在改變么？
Sure, Don, it stays light later in the summer and gets dark earlier in the winter.
當然了，唐，夏天白天長些，冬天天黑得早些。
No, that's not it. I mean the whole day feels longer.
不，我說的不是這件事。我的意思是一整天感覺變長了些。
I'm not sure that's possible, Don aren't days always 24 hours long?
我不確定它是不是真的，難道一天不總是24個小時么？
Well, it actually takes 23 hours, 56 minutes, and 4 seconds for the Earth to rotate on its axis.
其實，實際上，地球繞地軸自轉一周需要23小時56分零4秒。
But in fact the Earth's rotation is slowing down all the time because of the gravitational pull of the moon.
但實際上，因為有月球的萬有引力作用，地球自轉一直在變慢。
Does this mean that the days really do feel longer?
這就意味著一天真讓人覺得變長了？
Nope. The moon slows us down by about two milliseconds a century, so that even 1 million years ago days were only twenty seconds shorter.
不。每過一個世紀，月球使我們慢了2毫秒。因此，即使比起一百萬年前的某一天，現在也僅僅慢了20秒。
I doubt I would have noticed that.
人們會注意到么？
Maybe not a million years ago. But 400 million years ago days were 21 and a half hours long, which you would have noticed.
可能不是一百萬年前，而是4億年前的某一天，當時一天長21.5小時，這樣你可能就能注意到。
What you really would have noticed is that the time it takes the Earth to get around the sun hasn't changed, so that back then there were 400 days a year.
你真正能意識到的是：地球繞著太陽公轉的時間沒有改變，所以那時一年有400天。
Scientists have found fossil evidence from tropical corals that existed at that time, and they have about 400 daily growth rings per year.
從存活在那時的熱帶珊瑚中，科學家已經發現了化石證據。它們每年大約有400個生長日輪。
So someone was enjoying all those extra sunny days.
所以過去的人能享受這些多出來的日子。
