Earth's Days Weren't Always 24 Hours Long...

On Earth, we taken for granted the fact that days are precisely 24 hours long. However, this wasn't always the case, as the length of a day has varied from between 5 and 24 hours long. This duration has been impacted by tidal friction, asteroid impacts, plate tectonics, and major earthquakes, all of which will be discussed in today's video.

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Google Earth imagery used in this video: ©Google & Data Providers

Various licenses used in sections of this video (not the entire video, this video as a whole does not completely fall under one of these licenses) and/or in this video's thumbnail image (and this list does not include every license used in this video and/or thumbnail image):

Sources/Citations:
[2] U.S. Geological Survey

0:00 24 Hours
0:31 Day Lengths
2:24 Asteroid Impacts
2:57 Major Earthquakes
3:56 Ice Age & Glaciers

[Nightscape_]

My favorite part about being retired is sleeping in with my dog whenever I want. I don't even look at the clock anymore!

[scillyautomatic]

It is fascinating that, even though the length of the days may change over eons, the earth's rotation and the relative position of the moon are so constant (for pretty much all of human history) that we are able to measure out long periods of time with incredible accuracy. Heck, even the Aztecs extended their calendar with almost perfect accuracy.

[Phytologics]

One thing to add that is analogous to glaciers on land is the increase in rotational speed caused by the mass of water that humans have brought above sea level from dams and reservoirs. Using the skater analogy, one would think that this would have slowed rotation but almost all of the large dams are at mid latitudes so the overall effect is moving mass closer to the axis which increases rotation. The effect is milliseconds but it's very interesting nonetheless.
Keep up the good work! You always have good, thought provoking content which I thoroughly enjoy!

[gwendolenshepard]

I feel like science has to figure out so many variables at the same time to get an answer. It reminds of an act where the performer keeps multiple plates spinning. Thanks for making it easy to understand.

[TheSpaceEnthusiast-vlwx]

Thanks as always, Geology Hub! This topic is very interesting, especially towards the end!

[xwiick]

Thanks for all the hard work on these videos!

[LEDewey_MD]

Fascinating subject. It would be great if someone made a CGI showing what the Earth and Moon were like in the Hadeaen and Archeaen eons, with the Moon appearing ten times larger in the sky and rotation of Earth producing 5-12 hour days!

[pauljensen]

Would have gotten here sooner, but got stuck behind a Taco Bell advertisement.

[MossyMozart]

Wow, Mr Hub! This was enthralling. Thank you.

[MikkellTheImmortal]

This was a very interesting episode.
It does well to highlight just how many factors there are involved in the simple rotational speed of the planet.

[AaronGeo]

Imagine sleeping or going to work/school in the Eoarchean period

[AndreaCrisp]

So fascinating! Thanks for sharing.

As someone interested in geology and outer space have you done a video explaining why the Earth rotates and the impact of that on life and, of course, how it ties into geology? We keep finding planets in the Goldie Locks zone, but most seem to be tidally locked.

Anyway, love your content. Thank you!

[laughingoutloud]

You're a fantastic educator! Thank you for explaining this perfectly - I always add too many words 😊

[Antonowskyfly]

For some reason I run on a 28 hour long cycle. I can only surmise I’m from the future.

[daveselbow]

that extra second is gonna throw my routine right off

[korodyj]

So when we say that the earth is 4.6 billion years old.. does that mean we’re using our current year to calculate that time or that technically more days or years would’ve occurred during that time period because they might’ve been shorter at the time? I realized that the days were shorter but now my mind is semi blown thinking about how more days technically passed relative to the rotation at the time. Something I just never thought of until now.

[GAMakin]

SHUCKS! Now I know why I missed that job interview 3-billion years ago! I had my alarm set for 11:30...
😐

[WildAlchemicalSpirit]

Awesome! I've been wanting a breakdown on this! Thank you! ✨⌚✨

[medicinemanvids]

I wonder when days will be one day long 🤔

[AbAb-thqe]

0:11 No they aren't actually. Experiments have been done with people living for several months in deep caves with no clocks and it was discovered they gradually moved to a 10 hour cycle rather than a 24 hour one. We are quite flexible in our day length.