Why today is a #leapsecond longer

Today will be a bit longer than most other days – by a whole second.


by Jack White |
Published on

It’s called a leap second and, according to NASA, it’s a way of dealing with the fact the Earth’s orbit is slowing.

At midnight tonight clocks around the world will stop and we’ll all gain an extra second. It’s kind of exciting – the clock will read 23:59:60 before the new day starts.

“Earth’s rotation is gradually slowing down a bit, so leap seconds are a way to account for that,” NASA said in a statement.

There are 86,400 seconds in a day. Back at the start of ‘time’, a day was measured by how long the took to go from noon (its highest point) to noon again.


But now seconds are measured with atomic clocks. While this is much more feasible, a year still occurs with one full rotation of the Earth.

Because of the slight differences of time between the year and the second that give us the ‘leap’.

It’s basically a tiny difference that the second and year can agree on – if we didn’t have a leap second eventually time would shift so much that 1pm would essentially become noon, because that’s when the sun would be at its highest point.

Many have argued that this wouldn’t be a bad thing. Would noon being an hour make a huge difference to your life? Probably not.

But, on the other hand, if all these shifts can change noon, where does it stop?

Some conspiracy theorists have claimed leap seconds are very bad, and it’s just a sign that the world will eventually slow down so much that it will stop. But this is probably not true.

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