Hacker News Board Hacker News, browsed like a classic message board
Live data from Hacker News

All of Earth's water in a single sphere (2019)

usgs.gov

Post reply on HN
Print view View original

91–100 of 290 posts

Re: All of Earth's water in a single sphere (2019)

#91

Post by mmooss »

akira2501 wrote: post #39
rmah wrote: post #30

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…

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.

I thought the border with space is generally (and arbitrarily) said to be the Kármán 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.

Re: All of Earth's water in a single sphere (2019)

#92

Post by maxbond »

PaulHoule wrote: post #53
drewg123 wrote: post #40

Earlier quoted context omitted.

So, crash Ceres into Mars, and we have made a huge step towards terraforming?

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.

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.)

Re: All of Earth's water in a single sphere (2019)

#93

Post by njarboe »

lanna wrote: post #68
laweijfmvo wrote: post #55

Earlier quoted context omitted.

> 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!

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.

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.

Re: All of Earth's water in a single sphere (2019)

#95

Post by jameshart »

myself248 wrote: post #22

Turn Randall Munroe loose on this idea and be prepared for unspeakable devastation as a tsunami of Lovecraftian proportions wreaks havoc on the planet...

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

Re: All of Earth's water in a single sphere (2019)

#96

Post by staplers »

Sparkyte wrote: post #76
kevinkeller wrote: post #32

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-..…

We could probably terraform Mars if we crashed Europa into Mars.

Might have some "slight" orbital and shrapnel repercussions..

Re: All of Earth's water in a single sphere (2019)

#97

Post by wildzzz »

Sparkyte wrote: post #76
kevinkeller wrote: post #32

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-..…

We could probably terraform Mars if we crashed Europa into Mars.

And then we completely skew Mars's orbit until it crashes into the sun or is flung out of the solar system.

Re: All of Earth's water in a single sphere (2019)

#98

Post by oorza »

sfink wrote: post #59

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.

Closer to a bowling ball that picked up a drop of beer from your hands.

Re: All of Earth's water in a single sphere (2019)

#100

Post by YVoyiatzis »

umvi wrote: post #16

> 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)

Water dissolving and removing There is water at the bottom of the ocean
Post reply on HN