Full disclosure: I wrote much of this while suffering the ill effects of staying up late grading papers and the gloominess of winter’s darkest hour. And at the end of a long night, oh how I longed for just 1 extra hour to get that coveted long, full night of rest!

How long is a day?

I often have a hard time falling asleep. It’s late, the house is quiet, I’m tired, and yet I can’t sleep. It’s as though closing my eyes is somehow giving up on the day, like I could stay up just a little longer and learn something new, start a new project. And my last thought of the day is more often than not, “If I just had an extra hour…” I don’t think it’s too much to ask for a 25 hour day. I could do most of the things I wanted to do and still get a comfy 8 hours of sleep. Well, for this reason and many more, I probably should’ve been born a beaver (more on this in the next issue). Since I’m not a beaver I suppose I’ll have to wait for the future, go to mars, find a black hole, or travel the speed of light to get that elusive 25 hour day…

Of days past

A battle between a utahraptor and Brontomerus, much like the battle at the beginning of Raptor Red

I love dinosaurs. Love ’em. I’m grateful to Robert Bakker for his book Raptor Red, for his ability to translate cold fossils into a well-considered and touching portrait of Red, a female utahraptor. The book follows her through a particularly trying year as she struggles to survive in the harsh Cretaceous wilds. Her year is packed raising her young, taking down Astrodons, hunting in collaboration with pterosaurs, and fending off herds of Deinonychus. She lives more in a year than most animals do in a lifetime. But before you feel dwarfed in her shadow, like you wasted 2021, she did have 5 extra days in her year to get it all done.

You see, back in the Cretaceous, the earth was spinning faster than it spins today. In one full orbit of the earth around the sun, Red would see 370 sunsets and 370 sunrises crest over the arid mountains. In the 100 million years since her last sunset, a lot has changed, including the number of days in a year. As long as we’ve had tidal shifts, our planet has gradually been slowing it’s rotation (source). To balance it out, though, while there were more solar days in a year, a year was still 8,766 hours. This sadly means that each of Red’s 370 days were shorter than ours, coming it right around 23 hours and 40 minutes. A time machine to take me back in time would likely not make me more productive.

As the figure skater brings her arms in to her chest she starts to spin faster and faster

Why we’re slowing down


Imagine, if you will, a figure skater spinning around. Her arms extend gracefully out and as she draws them into her chest her rotation speeds up to dizzying levels. She extends her arms and comes to a graceful halt. The moon and the earth are caught in a similar dance. We can measure quite accurately that the moon is slowly drifter farther and farther from the earth, about 1.5 inches per year. As the moon gets farther away, the earth’s rotation around it’s axis slows too.

Dimetrodon grandis warming up at sunrise

The further back we go, the closer the moon was to us, so the faster we were spinning. Back to the Age of Amphibians some 300 million years ago, and we could have shared a meal of raw Eryops with our great great (insert lots and lots of greats here) great grandparents, who were pelycosaurs (mammal-like reptiles and the common ancestor of all mammals). But we’d need to be quick in catching our food as Pangea’s days were just 22.5 hours long.

It’s a long way back to amphioxus (song), the common ancestor of all vertebrates, 530 million years  back. For these bizarre-o fish-ish critters, a day was just 21 hours long. Surely their circadian rhythms were centered around these 21 hour cycles.

And I can’t help but think about how I would have fit it all wants and needs into a day back then? Would I skip breakfast and go right to lunch? Maybe if humans had evolved back then we would only need 6 hours of sleep 6, not 8? Or would we not have evolved because there wouldn’t have been enough time in a day to get enough food to fuele our brains? And the dinosaurs, what about the dinosaurs? If – er rather when – we finally open the gates to Jurassic Park, will the dinosaurs struggle to adjust their internal clocks to a 24-hour circadian rhythm?

Of days future

To infinity and beyond

I don’t have answers to those questions, but I’m also interested in more, not less, day length. Which turns out is easier to come by than traveling back in time. I can travel forward in time! Sure it’ll take some daily maintenance to keep my watch in sync, but in the future I’ll have time to learn origami and still get my full 8 hours of sleep in.

How much extra time will I have? If I land 50,000 years in the future, I’ll need to add a leap second every day to keep my clock accurate. As the planet continues to slow its rotation around its axis, 3 million years on, I’ll get an extra minute of sleep every day. Personally, I’d rather wait for Amasia the next supercontinent that’s already in the making. In 180 million years in the future, after Amasia has already formed, the planet will have slowed to where days are 25 hours long. 

Alternative ways to add an hour

I don’t need to wait 180 million years. I could just as easily get an extra hour of sleep tomorrow if I could blast the moon farther out into space. Or if I could magically increase earth’s mass (this would increase its gravitational pull and gravity slows time down, like in the movie Interstellar). I could also hop on a speedy plane and live out my days flying in the direction of earth’s rotation (the Hafele-Keating experiment). Or I could just sign up for Mars One – a day on Mars is a perfect 25 hours long! That seems like just the place for me.

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