Did You Know That the 24-Hour Day on Earth Was Not Always 24 Hours?

Amaze Lab

The Earth rotates completely once every 24 hours, but it’s getting slower and slower as the Moon moves further away. However, when the planet was only around 2-and-a-half billion years old that wasn’t the case and a day here was only 19.5 hours.

Transcript

00:00The Earth rotates completely once every 24 hours, but it's getting slower and slower

00:08as the Moon moves further away.

00:10However, when the planet was only around 2.5 billion years old, that wasn't the case,

00:14and a day here was only 19.5 hours.

00:17Experts say that was a constant for around 1.6 billion years, and now they might finally

00:22know why.

00:23Despite being nearly 240,000 miles away, the force the Moon exerts on our planet is substantial.

00:29After all, it's responsible for tidal effects that we can witness every day.

00:32But experts say that its pull on Earth is also counteracted by atmospheric forces exerted

00:36on us by the Sun.

00:38In fact, the Sun's force is so powerful, University of Toronto researchers say a day

00:42on our planet would be 60 hours at this point if only the Moon was affecting our spin.

00:46So how is Earth held in a constant 19.5 hour day for so long?

00:50Well, the researchers say that our former atmosphere played a big role.

00:53A warmer atmosphere means it was larger, and larger things tend to spin slower.

00:57However, experts say that resonance, or when waves move through the warmer and larger atmosphere

01:02at a particular altitude and velocity, synchronize.

01:05And via computer simulations, they were able to visualize that synchronicity with the waves

01:09traveling around the planet at a speed perfectly divisible by the just under 20 hour day length.

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