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Duration:06:22
Uploaded:2018-06-08
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According to a new model, days on Earth used to really fly by, and today Pluto has wind-swept dunes made of very weird sand.

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Sources:
http://science.sciencemag.org/content/sci/360/6392/992.full.pdf
http://www.latimes.com/science/sciencenow/la-sci-sn-pluto-methane-dunes-20180531-story.html#nws=mcnewsletter

www.pnas.org/cgi/doi/10.1073/pnas.1717689115
https://www.eurekalert.org/pub_releases/2018-06/uow-ttm053118.php
http://www.indiana.edu/~geol105/images/gaia_chapter_4/milankovitch.htm
https://www.packtpub.com/big-data-and-business-intelligence/bayesian-analysis-python
https://towardsdatascience.com/probability-concepts-explained-bayesian-inference-for-parameter-estimation-90e8930e5348
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Images:
https://en.wikipedia.org/wiki/File:Earth_formation.jpg
https://www.nasa.gov/image-feature/space-station-crew-sees-lots-of-clouds/
https://www.nasa.gov/image-feature/galileo-earth-and-moon
http://www.eso.org/public/usa/videos/eso1436c/
https://commons.wikimedia.org/wiki/File:Nh-pluto-in-true-color_2x_JPEG-edit-frame.jpg
https://en.wikipedia.org/wiki/File:Arbol_de_Piedra.jpg
https://commons.wikimedia.org/wiki/File:Sahara_desert.jpg
https://en.wikipedia.org/wiki/File:Pluto-01_Stern_03_Pluto_Color_TXT.jpg
https://en.wikipedia.org/wiki/Sputnik_Planitia#/media/File:Mountainous_Shoreline_of_Sputnik_Planum_(PIA20198).png
https://commons.wikimedia.org/wiki/File:Blue_hazes_over_backlit_Pluto.jpg
https://commons.wikimedia.org/wiki/File:PIA19947-NH-Pluto-Norgay-Hillary-Mountains-20150714.jpg
https://www.nasa.gov/image-feature/pluto-s-brilliant-heart
https://www.istockphoto.com/vector/sun-rising-background-on-landscape-hill-and-tree-gm815511810-132059067
[ ♪ Intro ].

Sometimes, it just feels like life would be easier if the days were a little longer. You’d have more time to spend with family or sleep or start another YouTube channel.

But the next time you’re wishing for a few more hours, you can be thankful you weren’t around 1.4 billion years ago. Thanks to our good friend the Moon, days on Earth were around six hours shorter back then. These results were published on Monday in the Proceedings of the National Academy of Sciences.

And while this is something we’ve known before, what’s special is the model the researchers created to confirm it. It allows them to look deep into the early history of the solar system — and it could have a lot more to teach us. Researchers are always trying to understand the processes that shaped the early Earth, and for good reasons.

Besides helping us figure out our origin story, it can also help us understand other worlds in the solar system and beyond the solar system. One way we can study the Earth’s climate specifically is through processes called Milankovitch cycles. They track things like a planet’s rotation rate, how it wobbles on its axis, and how tilted and circular its orbit is.

All of those things affect how much direct sunlight a planet gets. And on Earth, these factors add up to produce a cycling of warming and cooling on a ten-thousand to one-million year time scale. To be clear, though, they do not mean climate change isn’t also happening and that it isn’t also caused by humans.

Because it is. Researchers can track Milankovitch cycles in the geologic record, in things like isotope ratios, rocks, and ice cores. Still, these methods aren’t very reliable for really old samples — especially those older than around 50 million years — so it’s hard to look into the distant past.

There’s also a lot we don’t know about Earth’s orbit and its relationship to other planets from back then, so it’s difficult to extrapolate climate cycles from that alone, too. That’s where this new model came in. By combining geologic evidence with our knowledge of orbital mechanics, this team was able to bypass a lot of those limitations.

As a result, they got one of our clearest looks yet into the early solar system. They used a technique broadly called Bayesian statistics or Bayesian inference, which is wildly important to modern science. It’s used in particle physics and hydrogeology and cell biology — you name it, you can Bayesify it.

Basically, you start with some initial model, calibrate it to data, then update your model. Over time, you get an increasingly precise and probable explanation for whatever phenomena you want to explain. Kinda like the scientific method, but with statistics!

This new model covers things like the shape of Earth’s orbit and its gravitational interactions with the planets out to Saturn. But it also gave a special focus to how the Moon affects Earth’s climate and behavior. Among other things, it showed that, thanks to the Moon, our days were a little under 19 hours long 1.4 billion years ago!

Admittedly, though, this isn’t really surprising. Thanks to evidence from ocean models, we’ve known for a while that interactions between. Earth and the Moon have been steadily slowing our rotation rate.

But this new model was able to confirm that just using rock formations! This helps show how well-calibrated it is for those distant time periods. And it means we can apply it in ways we can’t with other methods.

More data would make it even more accurate, but right now, it can reach back in time really well. Now, we can start using it to get a better understanding of Earth’s early history and habitability, and the dynamics of the early solar system! Where would planetary science be without computers?

Where would any of us be? Meanwhile, on the other side of our little neighborhood, there’s more news from Pluto! Because even though it’s been almost three years since the New Horizons fly-by, we’re still learning more about what a lot of people thought would be a boring dwarf planet.

One of the major initial discoveries New Horizons made was that Pluto has an atmosphere. And this led scientists — and all the rest of us nerds — to wonder whether the atmosphere had any effect on Pluto’s topography. Wind can erode rock into all kinds of neat shapes, and sculpt big ol’ sand dunes like in the Sahara.

And now, thanks to an article published in Science last Friday, we know there are dunes on Pluto, too! Except, of course, they’re very different from the ones we’ve got here. First, their composition is different.

Earth’s dunes are made of little particles of rock — mostly quartzy stuff. But Pluto’s are made of methane. On Earth, methane is a gas — specifically, an odorless part of your fart gas.

And also the natural gas that people frack for, if you want a different comparison. But come on. Fart dunes.

Pluto is so cold that methane is solid there, and there’s a whole bunch of it existing in little particles. Now, we know that they make up some lovely, ripply dunes on Sputnik Planitia, the west half of Pluto’s heart. These dunes also form differently from ours.

The dwarf planet’s atmosphere is a lot thinner than Earth’s, so it can’t carve out dunes just by whipping across the methane plains. Instead, researchers think the process could be driven by day/night atmospheric cycles. Just like water vapor in Earth’s atmosphere condenses and freezes to form dew and frost, nitrogen gas in Pluto’s atmosphere condenses and freezes at night.

Then, in the morning, it sublimates and turns back into gas. As it does, it could puff up a bunch of methane sand, which would get caught in Pluto’s winds. And suddenly, you’d have 1001 Plutonian Nights.

Or something. Another cool thing is that, based on their surface features, the authors of the paper could also tell that these dunes have formed recently. Or at least, within the past 500,000 years, which is very recent for objects like planets.

That means these processes may be going on right now on Pluto’s surface! Which is way more dynamic and exciting then most people expected when New Horizons launched. And in case you were curious….

Yes, they figured this out with the help of a model, too. Thanks again, computers. And thank YOU for watching this episode of SciShow Space.

If you want to celebrate your love of science with the whole universe, we’ve added to our finds on SciShowFinds.com. Just today we’re adding fossilized Mesosaur Teeth and Ammonite Pairs. As well as this “wandering womb” pin inspired by our SciShow video on Hysteria.

I’m also excited that we are adding more trilobite fossils, because we sold out of those, and more copies of the book that made me love geology: The Story of Earth by Robert Hazen. There’s a bunch of good stuff on there right now that we love and have selected for you to check out. And just like last time, these are all available until we run out.

So go to SciShowFinds.com to get your own celebratory artifact of our edgeless universe. [ ♪ Outro ].