英语听力文摘 English Digest 704 多年前，一年长达400天

Years Ago, The Year Was 400 Days Long

Don: Ya?l, do you notice the days changing length over the course of the year?

Ya?l: Sure, Don, it stays light later in the summer and gets dark earlier in the winter.

Don: No, that’s not it. I mean the whole day feels longer.

Ya?l: I’m not sure that’s possible, Don aren’t days always 24 hours long?

Earth’s Rotation¹

Well, it actually takes 23 hours, 56 minutes, and 4 seconds for the Earth to rotate² on its axis³. But in fact the Earth’s rotation is slowing down all the time because of the gravitational pull of the moon.

Does this mean that the days really do feel longer? 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.

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.

400 Days Per Year

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.

Scientists have found fossil⁴ evidence from tropical⁵ corals that existed at that time, and they have about 400 daily growth rings per year. So someone was enjoying all those extra sunny days.

1 rotation   

n.旋转；循环，轮流

参考例句：

• Crop rotation helps prevent soil erosion.农作物轮作有助于防止水土流失。
• The workers in this workshop do day and night shifts in weekly rotation.这个车间的工人上白班和上夜班每周轮换一次。

2 rotate   

v.（使）旋转，转动；使轮流

参考例句：

• The doctor asked the patient to rotate his eyes.医生叫病人转动一下眼球。
• You can rotate the wheel with your hand.你可以用手转动轮子。

3 axis   

n.轴，轴线，中心线；坐标轴，基准线

参考例句：

• The earth's axis is the line between the North and South Poles.地轴是南北极之间的线。
• The axis of a circle is its diameter.圆的轴线是其直径。

4 fossil   

n.化石，食古不化的人，老顽固

参考例句：

• At this distance of time it is difficult to date the fossil.时间隔得这么久了，很难确定这化石的年代。
• The man is a fossil.那人是个老顽固。

5 tropical   

adj.热带的，热带的，炎热的

参考例句：

• You must grow these tropical flowers in a glasshouse.你必须把这些热带花卉种在温室里。
• This disease is widespread in tropical areas.这种疾病在热带地区蔓延很广。