The leap second explained

2022年10月14日

うるう秒は一瞬ですが、大きな問題を引き起こす可能性があります。真夜中になると、地球の自転速度に合わせるため、時計に 1 秒追加されます。短いタイムスケールではこれを無視できますが、100年後は1分ずれて、6000年後は1時間、72,000年後は12時間ずれるだろう。1年間で15分ほどずれることがありますが、誰も気づきません。さぁ今日は宇宙の神秘を感じてみましょう。(English) Leap second is only a second, but it could cause big problems. So at midnight, a second is added to the clock to match the speed of the earth's rotation. On shorter timescales, this can be ignored, but after 100 years, it will be off by a minute; after 6,000 years, it will be off by an hour, and after 72,000 years, it will be off by 12 hours. In one year, the time may shift by 15 minutes, but no one will notice. Let's feel the mystery of the universe today.

The leap second explained

It's only a second, but it could cause big problems.

At midnight an extra second will be added to our clocks to ensure we keep in time with the speed at which Earth spins - a bit like a leap year, just much shorter.

However, there's a warning that not everyone is ready for the shift.

And in Australia, more than 400 Qantas flights were delayed as a staff was forced to switch to manual check-ins.

This time around, there are some concerns about affecting stock exchanges and financial markets.

If you're lucky enough to have a digital clock showing Universal Coordinated Time when the leap second is added, you would see 23:59:60 for one second, as the last "minute" would contain one more.

You could ignore this over a short timescale.

After a century, the time given by our atomic clocks might disagree with the time given by the Sun by about one minute.

After 6,000 years, they might disagree by an hour.

After roughly 72,000 years, they might disagree by 12 hours, and according to our atomic clocks, midday would occur at midnight, according to the Sun.

Our timekeeping system is based on the average length of the day, which varies by 21 to 29 seconds in either direction throughout the year.

Over the year, our clocks can disagree with the Sun by as much as 15 minutes, and nobody notices.