Hurry up, planet Earth is running early and here's all you need to know about it

Lately, something odd is happening with the Earth. It has started spinning faster. On July 5, 2024, the Earth finished its daily spin quicker than on any day ever measured. Pics/iStock

Let me tell you a secret about the most ordinary thing in your life: the day.

We all believe a day is exactly 24 hours. Your phone says so. Your office says so. Your school timetable said so. But here is the truth - the Earth has never actually promised us 24 hours. A "day" is simply one full spin of the planet, and the Earth, like a slightly moody dancer, does not spin at exactly the same speed every time. Some days it turns a tiny bit slower. And lately, something odd is happening.

It has started spinning faster.

On July 5, 2024, the Earth finished its daily spin quicker than on any day ever measured. How much quicker? Less than the blink of an eye - a couple of thousandths of a second. You didn't feel it. Nobody did. So why are some of the smartest scientists in the world losing sleep over it?

Because of a machine we built that is too perfect.

For most of human history, the Earth itself was our only clock. The sun rose, the sun set - that was a day. Nobody argued with the sky.

Then, about 70 years ago, we built something extraordinary: the atomic clock. Forget the wall clock at home that gains a few minutes every month. An atomic clock is so accurate that if you had switched one on when dinosaurs roamed the Earth, it would barely have lost a second by today. It never gets tired, never runs slow, never needs winding.

And so, the whole modern world moved onto this new clock. Your phone's time comes from it. So does your bank transaction, your flight ticket, your Google Map location, every stock trade on Dalal Street. Modern life runs on the atomic clock's heartbeat.

But then we had a problem no one had before us. We had two clocks - the perfect atomic clock, and the old, moody Earth. And they don't always agree. It's like having one friend who is always exactly on time, and another who wanders in whenever she pleases. If the two must walk together, someone has to keep adjusting.

For 50 years, the adjustment was easy. The Earth was the slow friend - it has been gradually slowing down for millions of years (the Moon's pull acts like a gentle brake). So whenever the Earth fell too far behind, the timekeepers of the world would simply pause the official clock for one second and let the planet catch up. They called it the "leap second." It happened 27 times between 1972 and 2016. You never noticed. One night, somewhere in the world, a minute quietly had 61 seconds in it.

Simple. The Earth is slow, the clock waits. That was the rule. Then the Earth broke the rule.

Around 2020, scientists checking the measurements saw something they had never seen before. The Earth was not running slow anymore. It was running fast.

Year after year, it kept setting new speed records. And the strangest part? We don't fully know why. The best guess lies deep below your feet. The Earth is not solid all the way through - under the rocky crust flows a vast ocean of liquid, molten iron. Picture a raw egg spinning on your kitchen counter: the shell and the liquid inside don't move as one. Scientists believe that this liquid heart of the planet has, for some mysterious reason, slowed down - and to balance it, the outer Earth, the part we live on, has sped up. That's it. That's the honest answer of modern science: we can photograph black holes millions of light years away, but we cannot fully explain why our own floor is spinning faster.

Here's an even stranger twist. One thing is slowing the Earth back down - melting ice. As the great ice sheets of Greenland and Antarctica melt, the water spreads out across the oceans. A spinning skater slows down when she stretches her arms out; a planet does the same when its water spreads out. Scientists calculated that without this melting ice, our clock crisis would have arrived years earlier. Yes, you read that right - climate change is, in this one strange way, buying us time.

But it may only be a delay. If the Earth keeps hurrying, our timekeepers will face something that has never been done in history. Earlier, the Earth was slow, so we added a second. Now the Earth is fast - so we may have to remove one. One night, the clock would jump from 11:59:58 straight to midnight. The moment 11:59:59 would simply never exist. One second of your life, cancelled.

Sounds like nothing? Here's the worry. All the world's computers were built believing that time only moves forward, second by second, never skipping. Even adding a second - which we practised 27 times - once went wrong: in 2012, one extra second crashed websites and jammed airline check-in counters across the world. Removing a second has never been tested. Nobody truly knows what the world's banks, satellites and phone networks would do on a night when a minute has only 59 seconds.

So this October, timekeepers from over 60 countries will gather near Paris to vote on a way out: stop fiddling with seconds altogether, and let the perfect clock and the imperfect planet slowly drift apart - sorting out the difference maybe once in a century. It could be one of the most important decisions ever taken about something you will never notice.

And maybe that's the real story. For thousands of years, we obeyed the Earth's time. Now we have built clocks so perfect that the planet itself looks unreliable next to them - and we sit in committees deciding how to correct it, like schoolmasters marking a 4.5-billion-year-old student late.

So tonight, when your phone shows midnight, remember what that number really is: a delicate handshake between a machine that is never wrong and a planet that owes us nothing. The Earth is running fast. And somewhere, a room full of very nervous people is deciding what to do about the second that time forgot.

Nishant Sahdev is a physicist at the University of North Carolina at Chapel Hill, US. He chases ideas that refuse to stay in laboratories for your favourite Sunday mid-day.