The Earth heated up when its day was 22 hours long
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This sounds like a Bond villain plot. "Now, Mr. Prime Minister, I will slow the rotation of the Earth, causing an atmospheric resonance to build up that will obliterate the planet, unless you pay me one million dollars! Muwahahaha!"
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You know, it might actually cause just as much trouble at 33ish hours? I wonder if they modeled that.
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Perhaps there is a further resonance mode up there at which it would actually cool the atmosphere?
Global warming instantly solved – just spin up the Earth's rotation to 10x ;-)
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The exciting minimum in tidal drag happens if the day and month are the same (i.e. you put the moon in geostationary orbit).
Tides are fixed in one place on the world, but a couple orders of magnitude larger. So at current day length that would be 90+ meters. Probably only doable shortly after the Thea impact, though, and I have no idea what day length or geostationary distance was then.
Tides are fixed in one place on the world, but a couple orders of magnitude larger. So at current day length that would be 90+ meters. Probably only doable shortly after the Thea impact, though, and I have no idea what day length or geostationary distance was then.
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From the piece:
"And those of us who remember high school chemistry will recall that a gas that is warmed will expand."
ahhhh....PV=nRT
(be sure to get your units right
)
"And those of us who remember high school chemistry will recall that a gas that is warmed will expand."
ahhhh....PV=nRT
(be sure to get your units right
)
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I would think that the moon will be considerably farther away at that point, so perhaps tides will not be such high magnitude. At any rate, I think that the heating sun will have cooked off the oceans by then anyway.
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If it was a 22 hour day wouldn't it be Elevenses skies rather than Noontime skies?
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Nice post.
I sense that my current awareness and understanding of this topic needs to be increased!
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eduardopozo56
Wise, Aged Ars Veteran
So, can we hire spacex to drag the moon into Geostationary orbit?
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Made a brief attempt to figure if the time scale of how long it would take for the moon to slow us down that much and if it was on a scale that the gradual increase in Sun's output ( and eventually size) would make it irrelevant
.. But in trying to determine the rate of decleration I found out the earth is actually accelerating
Earth Sets New Record for Shortest Day
On June 29, 2022, Earth recorded its shortest day since scientists began using atomic clocks to measure its rotational speed.
www.timeanddate.com
So ... I gave up
Attachments
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I enjoyed your joke
Noon, from "nine", which used to mean 3pm and now means midday. The word can probably cope with meaning 11 o'clock. But would it be 11am or 11pm?
https://www.etymonline.com/word/noon
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Years ago, I saw an article about Thea impact theories. It said that Earth's day at that time was estimated at 5 hours. Tidal drag takes energy out of the rotation of both Earth and the Moon. It slows rotation and increases the radius of the Moon's orbit by about 36 cm per year.
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While I appreciate that this is being expressed in sensible units instead of stones per square cubit or something, you've done enough scientific writing to know better than to write units that way. "110 pascals" is a pressure. "110 Pascals" is a large French family reunion (or a crowd of cloned physicists). The editor should also be ashamed, except that I'm pretty sure editors are extinct in the wild.
If you prefer American sources, https://www.nist.gov/pml/owm/writing-si-metric-system-units
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Whoever wrote that guideline was fucking with their boss by choosing Celsius as the unit to demonstrate how the rules make no fucking sense
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I’m confused. Isn’t the whole premise of this article that the earth’s rotation is slowing down? So why does this linked article say it’s rotating faster than ever?!Made a brief attempt to figure if the time scale of how long it would take for the moon to slow us down that much and if it was on a scale that the gradual increase in Sun's output ( and eventually size) would make it irrelevant
.. But in trying to determine the rate of decleration I found out the earth is actually accelerating
Earth Sets New Record for Shortest Day
On June 29, 2022, Earth recorded its shortest day since scientists began using atomic clocks to measure its rotational speed.
So ... I gave up
This whole topic is clearly beyond my understanding :-/
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Though the Earth's rotation is continuing to slow down very gradually in the long run, sudden catastrophic events like major earthquakes sometimes speed it up very slightly so it's not a continual change from faster to slower.
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You should have read that article better. Here's a quote from the article you linked. "In general, over long periods, Earth’s spin is slowing. Every century, Earth takes a couple of milliseconds or so longer to complete one rotation (where 1 millisecond equals 0.001 seconds).
Within this general pattern, however, the speed of Earth’s spin fluctuates. From one day to the next, the time Earth takes to complete one rotation goes up or down by a fraction of a millisecond."
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Ok got it. I thought it was only slowing due to the moon, but didn’t get it was actually fluctuating (with a long term slowing trend).
Makes sense. Thank you kind sir!
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Yeah clearly I should! The guy above pointed it out, but I got it now. Thanks
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Should this be added to the Falsehoods programmers believe about time list on github?
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If you understood some science, you would not post stupid things. Models which are designed to look at one variable, or one set of initial conditions, may not be useful for things that they were not built for. If trying to predict water temperatures and coastal submersion on the East Coast over the next 20 years, to take a topic of current interest, we do not need continental drift, and probably not subsidence due to plate tectonics, although subsidence due to groundwater pumping would be included. Having a model tuned to Pangea would not be very useful in answering this question.
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In my limited understanding, this would no longer be a tide. Tide implies a daily variation, but in this model, the moon would be fixed above one place on Earth.
The result would be a fixed water level around 90m (if your height is correct) higher than the current average water level, located immediately below the moon, and possibly another +90m water elevation also on the other side of the Earth opposite the Moon. Decreasing to lower water level elsewhere, though probably not -90m, as there would be a band of lowered water level around the Earth.
I say fixed water level, but there would still be small cycles in water height from the Sun (daily) and other planets (mostly Jupiter I think).
Aside: This is one of the things that highly irritated me in the mostly excellent Cixin Liu book of short stories 'The Wandering Earth' (same author as the Three-Body Problem). In this short story, a highly dense alien spaceship arrives at Earth. Hovering above the sea, the density & mass of the spaceship causes a bulge in the water below, because the water is gravitationally attracted to the spaceship. The bulge is roughly 1km high. Our hero somehow pilots a boat up the bulge to immediately below the spaceship. Things happen. Afterwards, our hero swims down the bulge.
The part that irritates me is when Cixin says 'Swimming down the bulge was easier than going up because it was all downhill'.
NO! The surface of the sea bulge, by definition, is at equal gravitational potential at all parts. No part of it is 'uphill' or 'downhill' compared to any other part. If it was, then sea water would just flow to the new equilibrium.
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When the Theia impact (probably) happened, the day length was 18 hour and 41 minutes..
Geostationary distance would have been about 29,000 km above the equator.
The amount of mass that would have been in that orbit at any given time following the impact remains a matter of some debate in the community (read: the models disagree - a lot).
As my brother likes to say when driving down a street with timed lights "If you'll hit green at 25 mph, you'll also hit it at 50 or 100!"
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A 5-hour orbit has a height of roughly 8500 km, so if the moon were geostationary with that day length it would be about 45x closer than it is now.
Tidal forces scale with R^2, and I think the size of the tidal bulge is linear with the forces, so they would be about 2,000x bigger than current tides. So about 2 km.
Holy cow.
[edit] The 18 hour/29,000 km number JohnDeL cited gives ratios that are a lot saner, but still, a 68m tidal bulge is nothing to sneeze at.
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Tides go with the cube of distance, not the square, since they are due to the differential in gravity (which goes with the square).
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The more interesting one to model might be 27.5 hours, when instead of resonant reinforcement of the Lamb waves, you'd get yesterday's waves partially cancelling today's.
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Surely that should be high school physics? That’s where I studied the relationship between volume, temperature and pressure of a gas.
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The easiest way to get around all this is to define the day length at 24 hours, then adjust the lengths of hours, minutes, and seconds accordingly.
Obviously that would prevent any climate effects!
Obviously that would prevent any climate effects!
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Thanks for the correction. Apparently I need to re-read my mechanics book.
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It’s physical chemistry. I’ve only seen that covered in chemistry classes but different schools could quite reasonably do it differently.
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Thanks for the BIPM link, the contents of which are educational, if somewhat recondite. The Appendix offers an interesting history of developments in the standards field.
ETA: It occurs to me that the word ‘recondite’ is itself recondite.
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Stupid liberals will try and tell you that man (*) is capable of ruining the climate just by emitting harmless carbon dioxide using our puny cars, but our alleged ability to influence the planet is absolutely dwarfed by that little thing in the sky we all call the Moon.
(*) Just to be clear, women, by contrast, are, and have always been, entirely capable of ruining civilization due to their inherent foibles, which is why they need to be kept under strict control.
Edit: Sorry, I know this is a horrible post, it's just that lately I have been so bitter that I have actually taken to drinking coffee in my troll cave... 🫤
(*) Just to be clear, women, by contrast, are, and have always been, entirely capable of ruining civilization due to their inherent foibles, which is why they need to be kept under strict control.
Edit: Sorry, I know this is a horrible post, it's just that lately I have been so bitter that I have actually taken to drinking coffee in my troll cave... 🫤
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