有史以来最短的一天

由于地球自转速度莫名加快，7月9日成为有史以来最短的一天，比平时短约1.3毫秒。

今天你练听力了吗？

🤔️小作业：

1. Why does the author mention the 2011 Japan earthquake?

A. To show how past natural events have drastically affected Earth's orbit

B. To contrast known causes of spin changes with the current unexplained trend

C. To highlight the dangers of seismic activity on global timekeeping

D. To argue that only large disasters can change Earth's rotational speed

无注释原文：

Today, Earth is spinning faster than usual, and scientists are baffled

From: BBC Science Focus

Today will be one of the shortest days of the year, all because Earth's spin is inexplicably speeding up.

While the hours of daylight certainly last longer in the summer, the full day of 9 July 2025 will be 1.3 milliseconds shorter than average.

It takes our planet 24 hours, or 86,400 seconds, to make one full rotation around its axis, though this rate does fluctuate by a tiny amount. To track these changes, the International Earth Rotation and Reference Systems Service (IERS) continuously measures the length of the day to a high level of accuracy.

In 2020, the IERS noticed our planet was speeding up, and has been getting steadily faster ever since.

Their data predicts this year's shortest days are set to fall on 9 July, 22 July and 5 August, when the Moon is furthest from the equator.

The Moon has always subtly affected our planet's spin through tidal braking, where the Moon's gravitational pull causes our planet to bulge.

As well as creating the tides, this deformation slowly leaches away momentum from Earth's rotation, causing our planet to slow down by around 2 milliseconds per century.

This means that for the dinosaurs of the Triassic Era 200 million years ago, a day was just under 23 hours long. Meanwhile, in another 200 million years, the day will have extended to 25 hours long.

The IERS will occasionally add a leap second to the year to make sure high-precision clocks run on time. The most recent leap second was added on December 31, 2016.

When the Moon is further from the equator, the breaking effect isn't as strong and so these days are a tiny bit longer. However, the times being seen in recent years are a full half millisecond shorter than those seen prior to 2020.

While some events have been known to change Earth's rotation – the 9.0 Japan earthquake in 2011 shortened the day by 1.8 microseconds – no one knows what's causing the current trend.

The slowing won't have any catastrophic effect on our planet – it's far too short for anyone to notice – it did result in the IERS choosing to skip a leap second in 2025, and may have to take one back in 2029.

Whatever the cause, this is unlikely to be an ongoing effect, and our planet will eventually return to its long-term pattern of winding down.

- ◆ -

注：完整题目见本文开头；中文文本为机器翻译并非一一对应，仅供参考

含注释全文：

Today, Earth is spinning faster than usual, and scientists are baffled

From: BBC Science Focus

Today will be one of the shortest days of the year, all because Earth's spin is inexplicably speeding up.

由于地球的自转速度不明原因地加快，今天将成为全年最短的日子之一。

spin /spɪn/ 作动词，表示“（使）（尤指快速）旋转”，英文解释为“to (cause to) turn around and around, especially fast”举个🌰：The earth spins on its axis. 地球绕地轴旋转。

作名词，表示“旋转；转动”，英文解释为“the movement of something turning round very quickly”举个🌰：I hit something on the road, which sent the car into a spin. 我轧到了路面上的什么东西，整个车直打转。

📍spin (sb) a story/tale/yarn 表示“（为骗人或逗乐）杜撰故事，编造故事”，英文解释为“to tell a story, either to deceive someone or for entertainment”举个🌰：He spun some tale about needing to take time off work because his mother was ill. 他编了个瞎话，说他妈妈病了，他需要请假。They spun us a story about being in desperate need of money. 他们编了个瞎话，说他们急需用钱。

📍be spun into 演变为，转变为（将某些信息或情况转变或改编成另一种形式或叙述）

inexplicably /ˌɪn.ɪkˈsplɪk.ə.bli/ 表示“无法说明地；费解地”，英文解释为“in a way that cannot be explained or understood”举个🌰：Inexplicably, the men were never questioned about where the explosives came from. 令人费解的是，这些人从未被问及炸药的来源。

While the hours of daylight certainly last longer in the summer, the full day of 9 July 2025 will be 1.3 milliseconds shorter than average.

虽然夏天白昼时间较长，但2025年7月9日这一天将比平常缩短1.3毫秒。

It takes our planet 24 hours, or 86,400 seconds, to make one full rotation around its axis, though this rate does fluctuate by a tiny amount. To track these changes, the International Earth Rotation and Reference Systems Service (IERS) continuously measures the length of the day to a high level of accuracy.

地球自转一圈需要24小时，也就是86,400秒，但这个周期会有细微变动。国际地球自转和参考系统服务机构（IERS）一直在精确监测这种日长变化。

rotation /rəʊˈteɪ.ʃən/ 1）表示“轮作；换茬（农民有规则地改变地里种植的植物）”，英文解释为“the act by farmers of regularly changing which crops they grow in a field”如：crop rotation 农作物轮作。

2）表示“（尤指围绕一个固定点）旋转，转动”，英文解释为“movement in a circle around a fixed point”如：the speed of rotation 转速。

axis /ˈæk.sɪs/ 1）表示“轴（线）；中心线”，英文解释为“a real or imaginary straight line going through the centre of an object that is spinning, or a line that divides a symmetrical shape into two equal halves”举个🌰：The earth revolves around the axis that joins the North and South Poles. 地球围绕贯穿南北两极的地轴自转。

2）表示“参考轴线，基准线，坐标线”，英文解释为“a fixed line on a graph used to show the position of a point”

fluctuate /ˈflʌk.tʃu.eɪt/ 表示“（尤指持续）波动，起伏不定”，英文解释为“to change, especially continuously and between one level or thing and another”举个🌰：Vegetable prices fluctuate according to the season. 蔬菜价格随着季节变化而涨落。

In 2020, the IERS noticed our planet was speeding up, and has been getting steadily faster ever since.

早在2020年，IERS就发现地球的自转速度开始变快，而且这一趋势至今仍在持续。

Their data predicts this year's shortest days are set to fall on 9 July, 22 July and 5 August, when the Moon is furthest from the equator.

其数据显示，2025年最短的几天将分别出现在7月9日、22日与8月5日，这些时间段月球距离赤道最远。

equator /ɪˈkweɪtə/ 表示“赤道”，英文解释为“The equator is an imaginary line around the middle of the earth at an equal distance from the North Pole and the South Pole.”

The Moon has always subtly affected our planet's spin through tidal braking, where the Moon's gravitational pull causes our planet to bulge.

月球通过潮汐制动效应——即引力导致地球鼓胀——长期以来对地球的自转速度产生微妙影响。

Tidal braking（潮汐制动/减速）是指月球的引力作用在地球上产生潮汐隆起（即地球表面向月球方向鼓起），由于地球自转速度较快，这些隆起不是正对着月球，而是略微偏离，进而产生一个反作用力。这个反作用力：减缓地球自转速度（使一天变长）、使月球逐渐远离地球。这是一个非常缓慢但持续的过程，称为tidal braking（潮汐减速），即潮汐力对地球“刹车”的作用。

gravitational /ˌɡræv.ɪˈteɪ.ʃən.əl/ 表示“重力的，引力的”，英文解释为“relating to gravity or gravitation (= the force that attracts objects towards one another)”如：gravitational forces 重力，gravitational pull 引力。

bulge /bʌldʒ/ 表示“凸起；鼓起”，英文解释为“a curved shape sticking out from the surface of something”举个🌰：I wondered what the bulge in her coat pocket was. 我想知道她大衣口袋里鼓鼓的是什么东西。

As well as creating the tides, this deformation slowly leaches away momentum from Earth's rotation, causing our planet to slow down by around 2 milliseconds per century.

除了带来潮汐现象，这种地壳形变也会逐渐消耗地球的转动动能，导致自转速度每百年减慢约2毫秒。

deformation /ˌdiː.fɔːˈmeɪ.ʃən/ 表示“变形，扭曲”，英文解释为“the action of spoiling the usual and true shape of something, or a change in its usual and true shape”举个🌰：The deformation of the bones was caused by poor diet. 骨头的变形是由于饮食不良造成的。

leach /liːtʃ/ 表示“漂洗，过滤（尤指土壤）”，英文解释为“When a chemical substance leaches or is leached from a material, especially soil, it is removed by the action of water passing through the material.”举个🌰：The calcium, potassium, and magnesium ions are leached or washed out of the top soil into lower inaccessible subsoil. 钙、钾和镁离子被滤出表层土壤流入低层土壤却无法被吸收。

leach away原意指液体通过渗透将某物带走（常用于土壤中的养分被水“淋洗”走）。在这里是一个比喻用法，形容 地球自转的动量像被水慢慢“抽走”一样 缓慢流失。

momentum /məˈmen.təm/ 表示“动量，冲量；冲力；推动力；势头”，英文解释为“the force that keeps an object moving or keeps an event developing after it has started”举个🌰：Once you push it, it keeps going under its own momentum. 一旦你推动了它，它就会在自己的动量作用下持续运动。

This means that for the dinosaurs of the Triassic Era 200 million years ago, a day was just under 23 hours long. Meanwhile, in another 200 million years, the day will have extended to 25 hours long.

也就是说，2亿年前三叠纪的恐龙时代，一天还不足23小时；再过2亿年，一天或将变为25小时。

The IERS will occasionally add a leap second to the year to make sure high-precision clocks run on time. The most recent leap second was added on December 31, 2016.

为确保高精度时钟的准确运行，IERS偶尔会增加“闰秒”。上一次增加闰秒是在2016年12月31日。

leap /liːp/ 常指“跳，跳跃；突然的动作”，也可以表示“巨变；激增；提高”，英文解释为“a big change, increase, or improvement”如：a leap in profits 利润激增。

也可以直接作动词，表示“激增；猛涨；快速提高”，英文解释为“to increase, improve, or grow very quickly”举个🌰：Shares in the company leaped 250 percent. 公司的股票大涨250%。

leap year /ˈliːp ˌjɪər/ 表示“闰年”，英文解释为“a year that happens every four years and has an extra day on 29 February”

leap second表示“闰秒”。

When the Moon is further from the equator, the braking effect isn't as strong and so these days are a tiny bit longer. However, the times being seen in recent years are a full half millisecond shorter than those seen prior to 2020.

当月球远离赤道时，潮汐制动效应会减弱，白昼略有延长。然而，近年来的日长仍比2020年之前短了约0.5毫秒。

While some events have been known to change Earth's rotation – the 9.0 Japan earthquake in 2011 shortened the day by 1.8 microseconds – no one knows what's causing the current trend.

尽管有些事件会影响地球自转——例如2011年日本9.0级地震令日长缩短了1.8微秒——但目前尚无人知晓地球正持续加速自转的原因。

The slowing won't have any catastrophic effect on our planet – it's far too short for anyone to notice – it did result in the IERS choosing to skip a leap second in 2025, and may have to take one back in 2029.

这种加速不会对地球造成灾难性影响——变化微乎其微，难以察觉——但IERS已决定2025年不增加闰秒，未来或需在2029年“补时”。

catastrophic /ˌkætəˈstrɒfɪk/ 1）表示“灾难性的”，英文解释为“Something that is catastrophic involves or causes a sudden terrible disaster.”举个🌰：The water shortage is potentially catastrophic. 水资源的匮乏很可能是灾难性的。

2）表示“极糟的；失败的”，英文解释为“If you describe something as catastrophic, you mean that it is very bad or unsuccessful.”

Whatever the cause, this is unlikely to be an ongoing effect, and our planet will eventually return to its long-term pattern of winding down.

不论原因为何，这种自转加速趋势预计不会持续太久，地球最终会重返缓慢减速的轨道。

wind (sth) down 1）表示“（使）逐渐结束”，英文解释为“to end gradually or in stages, or to cause something to do this”举个🌰：Unfortunately, the party was just winding down as we got there. 不巧的是，我们赶到时聚会已接近尾声了。

2）表示“（使）（企业或机构）逐渐关闭，（使）慢慢倒闭”，英文解释为“If a business or organization winds down, or if someone winds it down, the amount of work it does is gradually reduced until it closes completely.”举个🌰：They're winding down their operations abroad because they're losing money. 因为亏损，他们正在逐步缩减海外业务。

wind down还可以表示“（劳累或担心之后）放松下来”，英文解释为“to gradually relax after doing something that has made you tired or worried”举个🌰：When he goes on holiday, it takes him the first couple of days just to wind down. 他去度假时，开始的几天只是放松放松。

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