[HN Gopher] All of Earth's water in a single sphere
___________________________________________________________________
All of Earth's water in a single sphere
Author : tigerlily
Score : 309 points
Date : 2024-08-13 18:32 UTC (4 hours ago)
(HTM) web link (www.usgs.gov)
(TXT) w3m dump (www.usgs.gov)
| PaulHoule wrote:
| ... it's about as much water as this place
|
| https://en.wikipedia.org/wiki/Ceres_(dwarf_planet)
| ceejayoz wrote:
| It would use up roughly the same _volume_ , but it'd be a lot
| more _water_.
|
| (Much heavier, I suspect, as well.)
| rachofsunshine wrote:
| Much _lighter_ , actually. Ceres isn't particularly dense as
| rocky bodies go (~2.2 g/cm^3, give or take), but it's still
| much denser than water (~1 g/cm^3).
| drewg123 wrote:
| So, crash Ceres into Mars, and we have made a huge step towards
| terraforming?
| PaulHoule wrote:
| Ceres could be taken apart with solar energy and rebuilt into
| a habitat much bigger than the Earth, never mind Mars. Ceres
| leads to the stars, Mars is just a dead end.
| maxbond wrote:
| Is there reason to believe the stars are less of a dead end
| than Mars? It's easy to imagine us making a huge bet on
| interstellar travel, and just dying in interstellar space.
| Surely there's untold abundance in the stars, but if you
| can't actually reach it, then it may as well be a mirage.
|
| Whenever I consider the possibility of interplanetary
| colonization, I come back to the conclusion that the only
| way to make it feasible is to reorient our economy towards
| sustainability in order to survive on Earth indefinitely.
| It's going to take a long, long time to develop the
| required technology, there's no real reason to believe
| artificial terraforming is even possible (since our sample
| size is 0), and even if it is it may take thousands or
| millions of years to complete.
|
| I'm not being facetious with that last part, in the absence
| of information to the contrary, we should expect technology
| that works via geologic processes to run on a geologic
| timescale. I personally think artificial terraforming is
| probably possible, and that we could accelerate it to be
| much faster than the natural terraforming of Earth. But
| accelerating a 2 billion year process to be 10000x faster
| still takes 200k years. (ETA: I suppose a lot of that was
| the planet forming and the rate of bombardment falling to
| something tolerable, which eg Mars was already subject to,
| so maybe call it 1B/100k years.)
| PaulHoule wrote:
| I did a lot of analysis for the problem of "build a solar
| sail factory on a carbonaceous chondrite asteroid that
| makes sunshades to deploy at the L1 point", particularly
| from a chemical engineering point of view.
|
| One interesting thing was that a lot of the chemistry
| involved was similar to the chemistry of decarbonization
| and carbon capture, particularly when you get CO2 as a
| waste product it is too precious to vent so you are going
| to feed it back into your "petrochemical" line.
|
| Objects like Ceres are the norm once you get out to the
| outer solar system, the difference is that Ceres is close
| enough to the sun for solar energy to be a good power
| source. Centaur objects, the moons of outer planets, and
| Kuiper belt objects like Pluto are similar but when you
| get far from the Sun you need to use a different power
| source such as D-D fusion.
|
| If a species became independent of sunlight it could take
| advantage of very generic objects that exist throughout
| interstellar space (comets, rouge planets, etc.) and make
| the journey in hops of (say) 100 years from one object to
| another. At that rate it would be possible to visit
| another star system in 10,000 years with a comfortable
| lifestyle. People like that might as well keep comet
| hopping but if they came across a star system I'd imagine
| they start some project like a Ceres megastructure
| because it is generic you can find some object like that
| and be able to establish a huge industrial base and
| population larger than the Earth with the same head end
| you've used all this time and same comfortable lifestyle.
|
| Earth would be priority two if that for those people.
| Grabby aliens might have disrupted Ceres but left the
| dinosaurs alone. But Ceres is here, so they were not.
| Ceres is such an attractive target that it should be a
| SETI goal to look for hardware left behind. Would be
| hilarious if they stole the Deuterium.
| maxbond wrote:
| It's interesting speculation. I just can't accept the
| existence of a spacecraft that can last 100 years without
| a catastrophic failure, or Ceres being reforged into a
| factory, or a nation of people who live entirely
| independent of Earth until I see it.
|
| Sometimes people talk about these things as if they are
| inevitable, but I would say there's an extremely good
| chance we go extinct without ever leaving this solar
| system (Voyager 1 notwithstanding). I think this is a
| valuable and grounding perspective in planning for the
| long term future of humanity, because we have to accept
| that that future takes place here on Earth and largely
| with the technology we already have. Space colonization
| is seductive, but like all silver bullets, impossible to
| operationalize within the constraints imposed on us by
| our situation.
|
| But it's probably not a useful one when picking SETI
| targets or generating other research ideas, and that
| stands on it's own merit.
| m3kw9 wrote:
| The height of the sphere isn't easy to visualize, should over lay
| height of water over Americas area
| g15jv2dp wrote:
| It's a sphere, the height is equal to the diameter that you
| plainly see on the picture.
| mecsred wrote:
| I'm trying to visualize the amount of water here, but it's
| hopeless unless an elementary student can calculate how many
| oil drums it would fill or football fields it would cover to a
| depth of one yard.
| didgetmaster wrote:
| The beauty of a sphere is that ANY dimension is EVERY
| dimension! Height, length, width, depth, etc. are all the same.
| rachofsunshine wrote:
| Assuming you mean "the depth of this water, if confined to a
| cross-sectional area the size of the United States", this is
| one of those nice Fermi estimation problems:
|
| - I know the US contains hundreds of millions of people, and
| the world contains a single-digit number of billions. So the US
| has about 10% of the world's people.
|
| - The US probably isn't particularly dense or sparse relative
| to other populated areas, so 1/10 the population should be 1/10
| the Earth's land area.
|
| - The Earth has twice as much ocean as land, and
|
| - The ocean is a few miles deep - let's say 5 - so there's
| about 10 miles of ocean depth per land area.
|
| - So compressing that to 1/10th the land area suggests the
| oceans should cover the US to a depth of about 100 miles.
|
| The exact answer, it turns out, is about 89 miles - really
| close, without looking up a single piece of information!
|
| https://www.wolframalpha.com/input?i=%28332%2C500%2C000+cubi...
| mensetmanusman wrote:
| Can't help but want to build that.
|
| Apparently all the mined gold in the world would fit inside a 5 m
| diameter sphere.
|
| Spheres are suspicious in hiding weight.
| guhidalg wrote:
| I've heard something like this before, but 5m is too small. The
| gold council reckons it's a little larger than that:
| https://www.gold.org/goldhub/data/how-much-gold
| nightpool wrote:
| The World Gold Council says:
|
| > If every single ounce of this gold were placed next to each
| other, the resulting cube of pure gold would only measure
| around 22 metres on each side
|
| So that can't possibly be right, you must be off by a factor of
| 10 or so at least--Wolfram Alpha says a 30m diameter sphere.
| vesinisa wrote:
| 27 meter diameter in fact. A 27-meter sphere is about 150
| times as voluminous as a 5-meter sphere.
|
| It's still a mind bogglingly small amount considering that
| humans have spared no toil, sweat and blood on industrial
| scale gold mining ever since the dawn of written history -
| and since gold is so valuable and hard to destroy, most of it
| should still exist to this day in form or another.
|
| Yet, if you smelted it all to a single object it would fit on
| a typical single family housing plot.
| dylan604 wrote:
| Spheres/circles are definitely surprising in how a seemingly
| small increase in radius changes the volume/area much more
| drastically. The cubing/squaring exponent is easily taken for
| granted.
| yzydserd wrote:
| I thought it was an Olympic sized swimming pool.
| vesinisa wrote:
| Close. About four of them, or a single 40-track one (the
| standard one has 10 tracks/lanes.)
| downboots wrote:
| Wouldn't a cube be a better choice for visualizing volume? A more
| complete version would do it alongside with minerals, biomass,
| etc
| mulhoon wrote:
| Why?
| margalabargala wrote:
| Humans are notoriously terrible about estimating volumes when
| things are curved and volume functions are exponential.
|
| A great example of this done in 8th grade science classes
| across the US is to put 100ml of water in a 100ml graduated
| cylinder, 150ml in a 1L beaker, and ask the class which has
| more. Humans are _awful_ at estimating how much volume the
| increased radius adds, and usually will say the 100ml.
|
| The problem only gets worse as we graduate from cylinders to
| spheres.
|
| We can all visually see _which_ sphere is bigger, but cannot
| come close to estimating how much bigger one is than another.
| AnimalMuppet wrote:
| Volume functions are _not_ exponential. They are
| polynomial.
|
| (Fair point that people are lousy at estimating even
| polynomial functions, though...)
| dylan604 wrote:
| > They are polynomial
|
| I don't think this word means what you think it does. Or
| I don't. Exponents are just the number the value is
| raised. Squaring a value just uses an exponent of 2 where
| cubing uses an exponent of 3. Polynomials are x^2 + x + 1
| type of equations. But admittedly, it has been 30+ years
| since I've thought about them at that level, so maybe I'm
| the one with fuzzy groking
| AnimalMuppet wrote:
| "Polynomial" meaning x^n. "Exponential" meaning e^x.
|
| Exponentials eventually grow much faster than
| polynomials, no matter what the exponent is.
|
| I mean, look, in v = x^3, the "3" is an exponent. But
| it's not an exponential _function_ because the variable
| isn 't in the exponent.
| pessimizer wrote:
| Exponential is c^x=y
|
| Polynomial is x^c=y
|
| Logarithmic is c^y=x
| tommiegannert wrote:
| Already eight years ago, I complained that people were
| using "exponential" where it doesn't make any sense. (See
| these two data points? Clearly exponential growth happend
| there. They're so far apart!)
|
| I believe the problem has increased exponentially since
| then. Now everyone is using exponentially in literally
| the same way as literally.
| fny wrote:
| They're comparing the sphere of water to the Earth which is a
| sphere.
|
| Also it's by the Water Science School, so it doesn't seem your
| definition of completeness was the intention.
| dylan604 wrote:
| Spheres are much more efficient. You must not have had the soap
| bubble question in an interview! Not everything in life
| conveniently fits in a box.
| bell-cot wrote:
| IIR, the Earth's mantle is understood to contain several times
| the total water content of the oceans, glaciers, lakes, etc.
|
| Obviously that water would be somewhat less accessible and
| quantifiable, but...
|
| Anyone familiar with the current geoscience on this?
| geepytee wrote:
| Does this include the water inside of living creatures?
| bowmessage wrote:
| Yes, from TFA:
|
| > and even the water in you, your dog, and your tomato plant.
| umvi wrote:
| > This sphere includes all of the water in the oceans, ice caps,
| lakes, rivers, groundwater, atmospheric water, and even the water
| in you, your dog, and your tomato plant.
|
| Does it include water in the mantle?
| (https://www.bnl.gov/newsroom/news.php?a=111648)
|
| or other non-liquid water for that matter like hydrates (ebsom
| salts, etc)
| moralestapia wrote:
| No, it doesn't. It includes all of the water in the oceans, ice
| caps, lakes, rivers, groundwater, atmospheric water, and even
| the water in you, your dog, and your tomato plant.
| FredPret wrote:
| "Groundwater" is a little ambiguous - H2O in the mantle is
| also "ground water", no?
| moralestapia wrote:
| It's not. The mantle is hundreds of kilometers further
| down.
| pfdietz wrote:
| No, that "water" is actually hydroxyl groups in minerals.
| chrisco255 wrote:
| No it comes out of the tap as water.
| DiggyJohnson wrote:
| No, it's completely inaccessible. Unless you are just
| playing word games, then sure.
| stcredzero wrote:
| The sphere for all liquid water seems to be close in size to
| the asteroid Ceres.
|
| https://lightsinthedark.com/wp-content/uploads/2013/06/ceres...
| dylan604 wrote:
| But would this sphere of water have enough mass to hold
| itself together as a sphere in space? Put aside it freezing
| into a ball of ice as a thought exercise.
| jesprenj wrote:
| Freezing? Wouldn't it boil instead due to the low pressure?
| dylan604 wrote:
| i knew there would be someone to just try to get out of
| the answer by failing to just go with the spirit of the
| question by being pedantic. even my own attempt at dispel
| pedantry just allowed for even more pedantry.
| Dylan16807 wrote:
| I don't know what you wanted.
|
| If you wanted to ask whether that amount can hold
| together and become spherical, then just by comparing to
| Ceres doesn't that make it plenty?
|
| It's not crazy to interpret "hold itself together" as
| more complex and including vapor escape.
| Retric wrote:
| Going from a liquid to a gas takes energy, which rapidly
| lowers the temperature of what remains. Net result most
| of the water freezes without some external energy source.
| Sublimation then lowers the temperature of the ice until
| near absolute zero, again unless there's some external
| energy source.
| rachofsunshine wrote:
| Depends on the temperature. At Earth-like temperatures,
| yes, it would. The transition between the two is around
| 175 K, give or take; below about 150 K ice is quite
| stable in a vacuum even over astronomical timescales;
| above 200 K it sublimates rapidly. (Surface liquid water
| is never stable in a vacuum or thin atmosphere
| regardless.)
|
| The rate of evaporation ramps up exponentially, from
| ~irrelevant at the bottom of that range to fast at the
| top. (For a body of this size, any resulting vapor would
| be quickly lost at these temperatures, so the rate of
| evaporation is effectively the rate of water loss as
| well.)
|
| This is why Jupiter can have icy moons (temperature ~100
| K), but ice sublimates quickly on Mars (~200 K).
| rachofsunshine wrote:
| The freezing-into-a-ball-of-ice is relevant here. A body
| that small can't hold on to water vapor at anything a human
| would consider a reasonable temperature; the average
| velocity of light gases at human-sane temperatures is high
| enough to overcome their escape velocity. See [1] for a
| log-log plot of what gases a body can hold onto - even
| Mars, which is much larger and denser than a Ceres-sized
| ball of water, has lost most of its water (although other
| factors like the solar wind are contributors there).
|
| A cold enough body, though, has a low enough vapor pressure
| that this isn't relevant even over cosmological timescales.
| That's why Europa can can have a stable icy surface. It's
| far enough from the Sun (and has a low enough albedo) that
| it's very very cold (about 100K), and at that temperature
| ice doesn't sublimate very much.
|
| TLDR: a Ceres-sized ball of water could hold itself
| together, but only as long as it stayed _water_. But it
| wouldn 't be able to. Either it'd be cold enough to freeze
| over at the surface, or hot enough to evaporate into vapor
| that would escape.
|
| [1] https://en.wikipedia.org/wiki/Atmosphere#/media/File:So
| lar_s...
| littlestymaar wrote:
| Given that water gets _lighter_ when cooling down right
| above its fusion temperature, and that ice is a pretty
| good insulator. You 'd have liquid water below an ice
| crust for a lot of time. It would eventually freeze
| entirely and be slowly eaten by the Sun's radiations. But
| that would take a pretty long time (well on a human
| scale).
| rachofsunshine wrote:
| Yeah, that's why I specified freeze _over_ and not freeze
| _through_ , although without doing the math I'm pretty
| sure it'd still freeze through on solar system timescales
| without radioactive (as in Earth's own mantle's case) or
| tidal (Enceladus, Europa, possibly Triton and Ganymede)
| heating.
| marcosdumay wrote:
| Yep, it's quite misleading since the region where they looked
| for water at all is an incredibly thin layer on the outside of
| the planet, but they show it all as if it applied to all of the
| volume.
| DiggyJohnson wrote:
| There's nothing wrong with their representation. You're
| describing a different comparison.
| IncreasePosts wrote:
| I'm not sure, but I know it's wrong, because I don't have a
| dog.
| Sparkyte wrote:
| Same question I've got, but I imagine USGS is only considering
| reachable surface, atmospheric water.
| Pat_Murph wrote:
| The wording of the legend description says all the war in, on
| and above the earth so we have to assume that is does take it
| into account.
| dredmorbius wrote:
| [delayed]
| YVoyiatzis wrote:
| _Water dissolving and removing There is water at the bottom of
| the ocean_
| dredmorbius wrote:
| [delayed]
| myself248 wrote:
| Turn Randall Munroe loose on this idea and be prepared for
| unspeakable devastation as a tsunami of Lovecraftian proportions
| wreaks havoc on the planet...
| maushu wrote:
| He already did it with a 1km diameter ball (https://what-
| if.xkcd.com/12/) and the destruction was terrifying. Please
| keep him away from these other bigger water balls.
| dylan604 wrote:
| It was just a friendly game of water balloons. We had no
| intent of destroying your planet.
| jameshart wrote:
| Literally just posted today: the video version of his What If?
| analysis of what would happen if you took that ball of water
| and dropped it on Mars:
| https://www.youtube.com/watch?v=FkUNHhVbQ1Q
| CodeWriter23 wrote:
| I think this is kind of useless information unless presented with
| other spheres for humans, structures, animals, plants, forests
| etc. for comparison. And ants.
| nemo44x wrote:
| And Olympic sized pools.
| rmah wrote:
| Just a few quick calculations to make it more relatable...
|
| They say the smallest sphere of freshwater lakes and rivers
| amounts to 93,113 cu km. There are 1 bil cu m per cu km. With a
| global population of 8.2 bil people, that comes to 11,355 cu m
| per person. That's a 22.5 meter wide/deep/tall cube (or about 7
| or 8 stories tall building).
|
| If we use the sphere that includes groundwater, 10,633,450 cu km.
| Then we end up with 1,296,762 cu m or a 109m wide cube per
| person.
| akira2501 wrote:
| Also.. the largest sphere has a radius of about 92 miles. It
| reaches to the edge of the atmosphere, and about 1/3 of the way
| to low earth orbit.
| laweijfmvo wrote:
| > The largest sphere represents all of Earth's water. Its
| diameter is about 860 miles
|
| Should be a radius of 430 miles, no?
|
| The image is very non-intuitive, IMO, because it's making the
| water appear so small compared to the entire planet (which,
| duh, obviously the water is only part of earth), but also
| drawing the planet that small really hides how friggin big
| the earth is!
| lanna wrote:
| Yes. The fresh-water lakes and rivers sphere definitely
| does not look like it could fill the Great Lakes next to
| it. I am not saying it doesn't, I'm just saying it doesn't
| look like it could.
| njarboe wrote:
| It does look very small in comparison to say Lake
| Michigan but most lakes are very thin. Lake Michigan is
| about 500km by 200km but only .085km(85m) average depth.
| JackFr wrote:
| Average depth of Lake Michigan is around 300 feet.
| Longest dimension is about 300 miles. If you drew a map
| of Lake Michigan on a sheet of letter-sized paper, the
| paper would be thicker than the average depth of water.
| cogogo wrote:
| Helped for me to compare to the moon. The water sphere has
| less than half the radius of the moon (~1080 miles). Think
| that's roughly 7-8% of the moon's volume if it were a
| perfect sphere.
| mmooss wrote:
| I thought the border with space is generally (and
| arbitrarily) said to be the Karman Line, at 100 km / 62.1 mi.
| I'm not nitpicking, just curious about other definitions.
|
| Also, I thought LEO typically begins around 180 km / 112 mi.
| madcaptenor wrote:
| I'm having trouble picturing a 22.5 meter cube. So consider a
| 200 sq m house; with ceilings of 2.5 m that's 500 cu m. So
| "your" water fills 22 houses.
| kevinkeller wrote:
| Largest ocean in our solar system isn't even on Earth,
| apparently:
|
| > ... Ganymede's ocean is even bigger than Europa's--and might be
| the largest in the entire solar system. "The Ganymede ocean is
| believed to contain more water than the Europan one," he says.
| "Six times more water in Ganymede's ocean than in Earth's ocean,
| and three times more than Europa."
|
| https://www.scientificamerican.com/article/overlooked-ocean-...
| teekert wrote:
| https://www.businessinsider.nl/earth-water-ice-volume-versus...
|
| Ganymede vs. Earth is indeed very surprising!
| JumpCrisscross wrote:
| > _Ganymede's ocean is even bigger than Europa's_
|
| Europa Clipper launches in October [1]. I've seen talk of
| crashing it into Ganymede to give JUICE novel data [2].
|
| [1] https://en.wikipedia.org/wiki/Europa_Clipper
|
| [2] https://www.space.com/europa-clipper-might-crash-into-
| ganyme...
| Sparkyte wrote:
| We could probably terraform Mars if we crashed Europa into
| Mars.
| staplers wrote:
| Might have some "slight" orbital and shrapnel repercussions..
| wildzzz wrote:
| And then we completely skew Mars's orbit until it crashes
| into the sun or is flung out of the solar system.
| littlestymaar wrote:
| If we had the technology allowing us to move a full
| satellite through the solar system, we could probably do it
| in a way that would just make Mars a bit closer to the sun
| so that the weather gets nicer (sure, if it gets too close
| to earth it's going to mess up with both orbits, but we can
| as well correct it when it happens, right?)
| ianburrell wrote:
| It would make Mars warmer. It would melt all the ice and CO2.
| It would give Mars an ocean. Of liquid rock. This is assuming
| that it doesn't destroy Mars completely. There might be
| enough fragments to make Solar System dangerous place and
| destroy life on Earth.
|
| Europa is the size of our Moon. Colliding it with Mars would
| be similar to the collision that formed our Moon.
| Mistletoe wrote:
| But would it stay on Mars? I thought the issue was there
| was no dynamo in the core, which lets solar winds strip it
| away. How long would it stay?
| ianburrell wrote:
| It would stay molten for millions of years.
|
| Not sure if Europa's water would be flung into space,
| make atmosphere, or make a boiling ocean.
| jzl wrote:
| I think this may have borrowed liberally from Corridor Crew's
| video about the same topic earlier in 2019:
| https://youtu.be/b3_Abb2Vqnc
| Smudo wrote:
| i want to se a Fluid simulation of this drop with an earth model
| rising-sky wrote:
| Pretty interesting juxtaposition considering water makes up about
| 71% of the Earth's surface, while the other 29% consists of
| continents and islands!
| digging wrote:
| Well, spill a glass of water on your kitchen counter and you'll
| find it suddenly makes up a large percentage of the counter's
| surface as well!
| rising-sky wrote:
| I'm aware, notice my comment specifically states "the Earth's
| *surface* " not just "the Earth". However, my kitchen counter
| is a flat surface, it's common knowledge the Earth isn't flat
| and the average ocean depth is 3,682 meters
| digging wrote:
| That was my point. The Earth isn't flat, but its surface is
| very smooth.
|
| You give the average ocean depth at 3.7km, but the Earth's
| diameter is about 12,742km, making those bumps pretty
| insignificant. If you cover your countertop in sandpaper
| and spill water on it, the difference in coverage going to
| be almost negligible.
| rising-sky wrote:
| Yea, just to be clear, I'm not disputing the image at
| all, my original comment is only an observation on the
| stark contrast when you juxtapose those two
| representations
| beAbU wrote:
| The earth is smoother than a billiard ball when accounting
| for relative size. Highly likely the earth is actually
| flatter than your countertop when accounting for size.
| yogurtboy wrote:
| I honestly find this extremely unsettling. There should
| definitely be more, though I don't really want our planet to look
| like Kamino
| sfink wrote:
| I long assumed that the Earth is a "water planet" because water
| is mostly what you see from a distance. It wasn't until I did the
| math that I realized that is really about wet rocks in space vs
| dry rocks in space.
|
| Earth isn't made of water, it's just a damp rock. Or a bowling
| ball that you squirted a dozen times with a spray bottle.
| spencerchubb wrote:
| > damp rock
|
| lol it's funny when you put it that way
| oorza wrote:
| Closer to a bowling ball that picked up a drop of beer from
| your hands.
| nwiswell wrote:
| This didn't sound right, so I did the math.
|
| The volume of all water is 1,386,000,000 km^3, which is then
| 1.386e+21 liters, or right about the same number of
| kilograms.
|
| The mass of Earth is about 5.972e+24 kg. So the percent
| fraction by mass is 0.0232%.
|
| A "drop" is typically estimated at 1/20th of one mL, which is
| then 0.05 grams. We can estimate the mass of a small-ish
| bowling ball at 5kg, or 5000 grams. 0.05 / 5000 * 100 =
| 0.001%.
|
| So it's an order of magnitude shy, but that's still closer
| than I expected! It's about 1 ml of beer on a bowling ball -
| a small splash. Or maybe a very large drop.
| silisili wrote:
| Thanks. This really put it in perspective for me better
| than the image or other analogies!
| arrowleaf wrote:
| You'd have to use the volume of earth, not the mass. Google
| tells me that lava is ~3x denser than water.
| rachofsunshine wrote:
| Lava is not really representative of the Earth as a
| whole, as it turns out. The mantle (which is the vast
| majority of Earth's volume) isn't a liquid, it's a
| squishy deformable solid. Magma that comes from the
| mantle is only liquid because of the removal of pressure
| or the addition of water; it wasn't liquid down there.
| And a lot of lava comes from crustal melting, not mantle
| material.
|
| Earth as a whole has a density about 5.5x that of water.
| ars wrote:
| Earth isn't even really a "rock", it's mostly a ball of iron.
|
| It's a ball of iron covered with rocks (i.e. metal oxides)
| cover with water (i.e. hydrogen oxide).
| zamadatix wrote:
| I don't buy it. Even allowing counting iron as separate from
| what rocks can be composed of (and using mass instead of
| volume) you still have 30.1%+15.1%=45.2% of the Earth as
| oxygen and silicon (which are most certainly part of what
| makes a rock) at which point you've already disproved the
| claim Earth is more a ball of iron than a ball of rock.
|
| A ball of iron covered with a ball of rocks is a more fair
| statement though, and I'd agree with that. It's just that
| center ball isn't most of what makes up the Earth (by any
| measure).
| ars wrote:
| https://s3-us-west-2.amazonaws.com/courses-images-archive-
| re...
|
| Everything up to and including the mantle is either iron or
| has a lot of iron. But to your point the mantle also has a
| lot of silica. So I guess it depends on your definition of
| "mostly".
| dredmorbius wrote:
| Mass is the defining characteristic of a quantity of
| matter. Given that much of the iron is under far higher
| compression than the outer layers of silicate rock, this
| also advantages iron.
|
| By mass, iron (32.1%) is still a minority constituent of
| the Earth.
|
| <https://en.wikipedia.org/wiki/Abundance_of_the_chemical_
| elem...>
| Intralexical wrote:
| "Squirt with a spray bottle" is a nice euphemism for throwing
| asteroids at.
|
| https://en.wikipedia.org/wiki/Origin_of_water_on_Earth#Aster...
| RIMR wrote:
| The ballpark math is easy to do in your head too. The diameter
| of Earth is 8,000 miles, and the deepest point in the ocean,
| the Mariana Trench, is only 7 miles deep. It's immediately
| apparent that the oceans are tiny by comparison to the rest of
| the mass that is Earth.
| aspectmin wrote:
| An interesting exercise is to do this exact same calculation
| with the atmosphere.
| tejohnso wrote:
| Neil DeGrasse Tyson says the earth scaled down to the size of
| a billiard ball would be smoother than any billiard ball ever
| made.
| netsharc wrote:
| > Earth isn't made of water, it's just a damp rock. Or a
| bowling ball that you squirted a dozen times with a spray
| bottle.
|
| Yeah, the image with the oceans being dry is wow-inducing... On
| further thought, of course it'd be very close a sphere, because
| gravity forces it to be. A sphere where e.g. a slice of it is
| water (imagine a clementine with one of its segments being
| water) would be very wobbly if even possible at all..
| bozhark wrote:
| "All the Earth's FRESH Water"
| losvedir wrote:
| Nope. That's the small (not barely visible tiny) ball.
| stronglikedan wrote:
| "all of Earth's water, Earth's liquid fresh water, and water in
| lakes and rivers"
| Sparkyte wrote:
| Not sure this is accurate as we've discovered that water can
| reside deeper in the Earth than previously imagined and in
| addition to that the density of water at the surface is different
| than at the bottom of the ocean. I suppose they are also
| accounting for the salt being removed too. But my argument is
| probably in the margin of error so what do I know?
|
| https://www.technology.org/how-and-why/what-would-happen-if-....
|
| So I feel like the USGS is exagerated.
| rachofsunshine wrote:
| The density of water at the bottom of the ocean is actually
| quite similar to the density on the surface; it differs by only
| a few percent. Gases compress proportionally to pressure, but
| liquids act more similar to solids and compress very little
| even under enormous pressures.
|
| The oceans are only about 3.5% salt by weight, so that doesn't
| make a huge difference, either.
| Sparkyte wrote:
| I figured it would be within 5% margin.
|
| I find this pretty interesting,
| https://phys.org/news/2023-11-reveal-earth-surface-
| penetrate...
| nashashmi wrote:
| Spheres could be a more viable unit of measurement instead of
| "Millions of Gallons".
|
| Imagine the headline: 500 million gallons of
| water expected to melt this year
|
| VS 1.2 microspheres of seawater expected to melt
| this year
| frabjoused wrote:
| Pertinent video that came out 4 hours ago:
|
| https://www.youtube.com/watch?v=FkUNHhVbQ1Q
| raldi wrote:
| Where is liquid fresh water besides lakes and rivers?
| hrunt wrote:
| Underground
| autophagian wrote:
| Groundwater, and swamp water, the post explains.
| schmichael wrote:
| > The blue sphere over Kentucky represents the world's liquid
| fresh water (groundwater, lakes, swamp water, and rivers).
|
| So the medium blue sphere includes groundwater and swamp water
| while the tiny dot does not.
| comboy wrote:
| Groundwater mostly, but also clouds (minuscule amount).
| jrflowers wrote:
| Fun fact: If you did this, everyone would die.
| pimlottc wrote:
| Plus every other nation on the earth would be mad at the US for
| taking it all
| itohihiyt wrote:
| This freaks me out, and I have no idea why...
| nemo44x wrote:
| It's about 554.4 trillion Olympic-sized swimming pools, if you're
| interested.
| srameshc wrote:
| We always talk about how scarce freshwater is but this image
| reprenstation has made it difficult to imagine how much supply do
| we have for an ever growing human population, the growing demand
| for water and how long will it last.
| asadm wrote:
| Does water leave earth when used?
| jumploops wrote:
| Let's find a large ice comet and direct it towards Mars!
| Aperocky wrote:
| That's actually a lot bigger than I thought - The largest
| asteroid Ceres would be 1/3 the diameter of this water sphere
| (860mi)
|
| That's a LOT of water.
| eh_why_not wrote:
| I was curious how much of this water we lose to space via
| evaporation. Looking around, apparently not much; only few
| molecules achieve escape velocity. But can't find a good
| calculation yet.
| sahmeepee wrote:
| This is similar to the idea that if you scaled the Earth to the
| size of a standard size 5 football and dried it off, you would
| barely be able to feel the mountains or trenches on the surface.
| The water is therefore a very thin film over the land in those
| terms.
| RIMR wrote:
| I'm sold. Let's do it!
| rishikeshs wrote:
| Does this include the water in all human made stuff like pools,
| tanks, etc and also water present in all organisms? Or is that
| negligible?
| lolinder wrote:
| > This sphere includes all of the water in the oceans, ice
| caps, lakes, rivers, groundwater, atmospheric water, and even
| the water in you, your dog, and your tomato plant.
| whutsurnaym wrote:
| From TFA: "This sphere includes all of the water in the oceans,
| ice caps, lakes, rivers, groundwater, atmospheric water, and
| even the water in you, your dog, and your tomato plant."
| utopcell wrote:
| Yeah, but also if you took all humanity and compressed it into a
| "meat sphere", it would only be 1km wide [1].
|
| [1] https://www.iflscience.com/blended-up-every-living-human-
| in-...
| bamboozled wrote:
| Helps one understand why pollution is such an insidious problem.
| andrewstuart wrote:
| Sounds like the water moon from Iain M Banks "The Algebraist",
| quote:
|
| _" I was born on a water moon.
|
| Some people, especially its inhabitants, called it a planet, but
| as it was only a little over two hundred kilometers in diameter
| 'moon' seems the more accurate term. The moon was made entirely
| of water, by which I mean it was a globe that not only had no
| land, but no rock either, a sphere with no solid core at all,
| just water, all the way down to the very center of the globe.
|
| If it had been much bigger the moon would have had a core of ice,
| for water, though supposedly incompressible, is not entirely so,
| and will change under extremes of pressure to become ice. (If you
| are used to living on a planet where ice floats on the surface of
| water, this seems odd and even wrong, but nevertheless it is the
| case.) This moon was not quite of a size for an ice core to form,
| and therefore one could, if one was sufficiently hardy, and
| adequately proof against the water pressure, make one's way down,
| through the increasing weight of water above, to the very center
| of the moon.
|
| Where a strange thing happened.
|
| For here, at the very center of this watery globe, there seemed
| to be no gravity. There was colossal pressure, certainly,
| pressing in from every side, but one was in effect weightless (on
| the outside of a planet, moon, or other body, watery or not, one
| is always being pulled towards its center; once at its center one
| is being pulled equally in all directions), and indeed the
| pressure around one was, for the same reason, not quite as great
| as one might have expected it to be, given the mass of the water
| that the moon was made up from."_
| insane_dreamer wrote:
| Shouldn't this say "surface water"?
| wrp wrote:
| "Consider a spherical ocean..."
| tamimio wrote:
| I would like to have a zoomed-in picture of that 'tiny'
| freshwater lakes and rivers to see its height. From this
| perspective, it doesn't add up. Just above it, the Great Lakes
| look far bigger, not to mention other lakes and rivers in the
| world.
| MalcolmDwyer wrote:
| The Great Lakes span across hundreds of miles, but the deepest
| point is less than a quarter mile, and most of it is much
| shallower than that. I.e., it's a super thin film over that big
| surface area.
| elfbargpt wrote:
| "Yes, Lake Michigan looks way bigger than this sphere, but you
| have to try to imagine a bubble almost 35 miles high--whereas
| the average depth of Lake Michigan is less than 300 feet (91
| meters)"
| abtinf wrote:
| 2019
| 2f0ja wrote:
| Reminds me of the short story 'Sea of Dreams'[1] by Liu Cixin.
| It's in one of his anthologies but I can't remember which one
|
| https://www.goodreads.com/book/show/61305943-sea-of-dreams
| mistercow wrote:
| I think it's important to keep in mind that if you did this same
| visualization on a planet with ten times Earth's radius, but the
| same ocean depth and water distribution, then the water blobs
| would seem even smaller in comparison to the planet.
|
| I'm just not sure it's a particularly useful illustration to
| compare the volume of water on a planet to that of the planet
| itself.
| brcmthrowaway wrote:
| Jordan Peelems next movie, FLOAT
| mikewarot wrote:
| It looks too small, perhaps there's more water tied up in the
| core and mantle than that?
|
| [1] https://www.bnl.gov/newsroom/news.php?a=111648
|
| [2] https://www.space.com/water-in-earth-core-forms-crystal-
| laye...
|
| [3] https://www.goethe-university-
| frankfurt.de/125691203/An_ocea...
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