一年曾有400天

錢潤荷

A： Do you notice the days changing length over the course of the year？

B： Sure， it stays light later in the summer and gets dark earlier in the winter.

A： No， thats not it. I mean the whole day feels longer.

B： Im not sure thats possible. Arent days always 24 hours long？

A： 你注意到了一年中每一天的長度都在改變嗎？

B： 當(dāng)然了，夏季白天更長，冬季天黑得更早。

A： 不，我不是說的這個(gè)。我的意思是整個(gè)一天的時(shí)間感覺變長了。

B： 我不太確定這是否可能。難道一天不是一直都是24個(gè)小時(shí)嗎？

Earths Rotation

Well， it actually takes 23 hours， 56 minutes， and 4 seconds for the Earth to rotate （自轉(zhuǎn)） once. But in fact the Earths rotation is slowing down all the time because of the gravitational pull （萬有引力） of the moon.

Does this mean that the days really do feel longer？ No. The moon slows us down by about two milliseconds （毫秒） a century， so that even one million years ago days were only twenty seconds shorter.

地球自轉(zhuǎn)

事實(shí)是，地球自轉(zhuǎn)一周需要23小時(shí)56分零4秒。但實(shí)際上，由于有月球的萬有引力作用，地球的自轉(zhuǎn)一直在變慢。

這是就意味著一天的時(shí)間真的讓人覺得變長了？不。月球每過一個(gè)世紀(jì)就讓我們變慢了兩毫秒。因此，即使是一百萬年前，每天時(shí)間比起現(xiàn)在也只變短了20秒。

Would People Notice？

I doubt I would have noticed that.

Maybe not a million years ago but 400 million years ago， days were 21 and a half hours long， which you would have noticed.

人們會注意到么？

我很懷疑我是否能注意到。

也許，不是一百萬年前而是4億年前的話，當(dāng)時(shí)一天是21.5小時(shí)，這樣你就注意到了。

400 Days per Year

What you really would have noticed is that the time it takes the Earth to get around the sun hasnt changed， so that back then there were 400 days a year.

Scientists have found fossil （化石） evidence from tropical corals （熱帶珊瑚蟲） that existed at that time， and they have about 400 daily growth rings per year. So someone was enjoying all those extra （額外的） sunny days.

一年400天

可能你真正意識到的是：地球繞著太陽公轉(zhuǎn)的時(shí)間沒有改變，所以那個(gè)時(shí)候一年有400天。

從存活于那個(gè)時(shí)候的熱帶珊瑚蟲的化石中，科學(xué)家已經(jīng)發(fā)現(xiàn)了證據(jù)。那個(gè)時(shí)候的珊瑚每年大約有400個(gè)生長日輪。所以那時(shí)的某個(gè)人可以享受這些額外的燦爛陽光。