Reply
 
Thread Tools Display Modes
  #1  
Old 05-22-2009, 12:52 AM
The Controvert The Controvert is offline
Guest
 
Join Date: Sep 2001
Location: Austin, TX
Posts: 3,763
Just how smooth is the Earth?

According to this post, the smoothness of the Earth is compared to ball bearings and billiard balls.

Yet, I have a hard time believing this statement. The human finger is pretty sensitive to small imperfections, if I ran my finger over a perfect scale replica of the Earth, would I or would I not be able to feel the mountains and other features?

How large would the replica need to be before this happens? Or how small does it have to be in order to feel perfectly smooth to the human finger?
  #2  
Old 05-22-2009, 01:01 AM
Sage Rat's Avatar
Sage Rat Sage Rat is offline
Member
 
Join Date: Mar 2004
Location: Howdy
Posts: 20,616
From the surface of the ocean, the Marianas Trench is 6.8 miles deep and Mt. Kilimanjaro is 3.7 miles high. So in total, that's a maximum difference of 10.5 miles for the surface of the planet. The Earth is about 4000 miles in radius. A pool ball is maybe an inch to an inch and a half in radius. Do you think you can perceive 2.6 thousandths of an inch (6.6 hundredths of a millimeter)?

And really we should take out the Marianas Trench since the spherocity of the Earth is aided by the ocean. So our 10.5 should be shrunk back to the 3.7 above the ocean.

(Though actually the bulge of the equator gives a total of 13 miles difference, which is the greatest overall difference, but is a smooth gradient rather than a bump like a mountain or trench.)

Last edited by Sage Rat; 05-22-2009 at 01:04 AM.
  #3  
Old 05-22-2009, 01:05 AM
exastris exastris is offline
Guest
 
Join Date: Apr 2005
Location: ObamAZ
Posts: 277
Quote:
Originally Posted by The Controvert View Post
The human finger is pretty sensitive to small imperfections, if I ran my finger over a perfect scale replica of the Earth, would I or would I not be able to feel the mountains and other features?

How large would the replica need to be before this happens? Or how small does it have to be in order to feel perfectly smooth to the human finger?
I've seen (and more importantly, felt) an exhibit like this. The Earth in question was about the size of a standard desk globe (what's that, maybe a foot in diameter or so?), and I was barely able to feel the smaller mountains. Definitely could feel the larger ones, but even they were surprisingly small. It was astonishing. I'm sorry I don't have exact numbers for you!
  #4  
Old 05-22-2009, 03:52 AM
jovan jovan is offline
Guest
 
Join Date: Aug 2001
Location: Japan
Posts: 2,964
This question has been answered by none other than the Bad Astronomer himself:
http://blogs.discovermagazine.com/ba...out-the-earth/

Quote:
According to the World Pool-Billiard Association, a pool ball is 2.25 inches in diameter, and has a tolerance of +/- 0.005 inches.
(...)
The Earth has a diameter of about 12,735 kilometers (on average, see below for more on this). Using the smoothness ratio from above, the Earth would be an acceptable pool ball if it had no bumps (mountains) or pits (trenches) more than 12,735 km x 0.00222 = about 28 km in size.

The highest point on Earth is the top of Mt. Everest, at 8.85 km. The deepest point on Earth is the Marianas Trench, at about 11 km deep.

Hey, those are within the tolerances!
  #5  
Old 05-22-2009, 07:11 AM
Malacandra Malacandra is offline
BANNED
 
Join Date: Jan 2003
Location: England, Britain, UK
Posts: 18,480
Quote:
Originally Posted by Sage Rat View Post
From the surface of the ocean, the Marianas Trench is 6.8 miles deep and Mt. Kilimanjaro is 3.7 miles high. So in total, that's a maximum difference of 10.5 miles for the surface of the planet. The Earth is about 4000 miles in radius. A pool ball is maybe an inch to an inch and a half in radius. Do you think you can perceive 2.6 thousandths of an inch (6.6 hundredths of a millimeter)?

And really we should take out the Marianas Trench since the spherocity of the Earth is aided by the ocean. So our 10.5 should be shrunk back to the 3.7 above the ocean.

(Though actually the bulge of the equator gives a total of 13 miles difference, which is the greatest overall difference, but is a smooth gradient rather than a bump like a mountain or trench.)
Why Kilimanjaro, out of interest? You know, what with Everest being way higher and all that.
  #6  
Old 05-22-2009, 07:14 AM
R. P. McMurphy R. P. McMurphy is offline
Charter Member
 
Join Date: Jun 2002
Posts: 3,883
Quote:
Originally Posted by jovan View Post
This question has been answered by none other than the Bad Astronomer himself:
http://blogs.discovermagazine.com/ba...out-the-earth/
And who said you can't get an education by hanging out at the pool hall?
  #7  
Old 05-22-2009, 08:48 AM
RickJay RickJay is online now
Charter Jays Fan
Moderator
 
Join Date: Jun 2000
Location: Oakville, Canada
Posts: 40,253
Quote:
Originally Posted by Malacandra View Post
Why Kilimanjaro, out of interest? You know, what with Everest being way higher and all that.
Everest is still far, far under the percentage tolerance allowable in an official pool ball.

It does seem hard to believe, I admit, but that's mostly because the enormousness of the Earth itself is kind of hard to comprehend. Everest looks really big when you're standing below it, but on the scale of the Earth it doesn't even qualify as a pimple.

The difference of .066 millimetres between lowest and highest points you'd be on a billiard-ball sized Earth is beyond visual perception and, since any specific relief point would actually be smaller than that, likely not perceptible to the touch. You can't even measure that with a ruler; you'd need a micrometer or a vernier or some such instrument that measures differences the eye cannot perceive.
  #8  
Old 05-22-2009, 09:01 AM
notfrommensa notfrommensa is offline
Guest
 
Join Date: Oct 2000
Posts: 11,724
Quote:
Originally Posted by Malacandra View Post
Why Kilimanjaro, out of interest? You know, what with Everest being way higher and all that.
Everest is the highest point in terms of sealevel, but because of the bulge of the earth (not a perfect sphere) that another mountain is the furthest from the center of the earth?

Chimborazo, in Ecuador, is the furthest point from the Earth Center, according to this admittedly vague article in wiki.

Since we are talking about "perceived roughness" of the Earth Kilimanjaro might be the highest peak, relative to its nearby surroundings. But I would think mountainous islands like Hawaii would have that beat.

Last edited by notfrommensa; 05-22-2009 at 09:02 AM.
  #9  
Old 05-22-2009, 09:33 AM
Hampshire Hampshire is online now
Member
 
Join Date: Jan 2003
Location: Minneapolis
Posts: 10,779
I'm still impressing people with the following fact we discussed here about a month ago in regards to the surface of the earth:

Run a cable around the circumference of the earth. Run another cable loop on top of that one but a foot higher. How much longer is the outer loop? ~6 feet.
  #10  
Old 05-22-2009, 09:41 AM
pipper pipper is offline
Guest
 
Join Date: Oct 2002
Location: Chicago
Posts: 327
Quote:
Originally Posted by Malacandra View Post
Why Kilimanjaro, out of interest? You know, what with Everest being way higher and all that.
notfrommensa is on the right track. It's because Kili is the world's largest/ tallest freestanding mountain (that is on land anyway. I think there are some underwater volcanoes that are larger).

In other words, the difference between the summit and the surrounding land is the greatest. Everest is higher, but since the surrounding land is also very high, the absolute difference is less.

Last edited by pipper; 05-22-2009 at 09:45 AM.
  #11  
Old 05-22-2009, 10:19 AM
SCSimmons SCSimmons is offline
Guest
 
Join Date: Mar 2001
Location: Arlington, TX
Posts: 3,264
Quote:
Originally Posted by Hampshire View Post
I'm still impressing people with the following fact we discussed here about a month ago in regards to the surface of the earth:

Run a cable around the circumference of the earth. Run another cable loop on top of that one but a foot higher. How much longer is the outer loop? ~6 feet.
Well, that's true of Jupiter or the Moon, too. Or a beach ball. It doesn't have anything to do with the circumference of the Earth, but with the fact that C = 2*pi*r.
__________________
-Christian
"You won't like me when I'm angry. Because I always back up my rage with facts and documented sources." -- The Credible Hulk
  #12  
Old 05-22-2009, 10:27 AM
DrCube DrCube is offline
Guest
 
Join Date: Oct 2005
Location: Caseyville, IL
Posts: 7,112
Quote:
Originally Posted by notfrommensa View Post
Everest is the highest point in terms of sealevel, but because of the bulge of the earth (not a perfect sphere) that another mountain is the furthest from the center of the earth?

Chimborazo, in Ecuador, is the furthest point from the Earth Center, according to this admittedly vague article in wiki.

Since we are talking about "perceived roughness" of the Earth Kilimanjaro might be the highest peak, relative to its nearby surroundings. But I would think mountainous islands like Hawaii would have that beat.
My understanding (no cite, sorry, maybe another poster will confirm) is that Everest is the highest point above sea level, Kilimanjaro is the highest mountain on land measured from the surrounding land to the peak, and that one of the Hawaiian islands (maybe Hawaii itself) is the tallest measured from base to peak if you accept that most of it is underwater.
  #13  
Old 05-22-2009, 10:37 AM
tdn tdn is offline
Guest
 
Join Date: Feb 2000
Posts: 35,871
Quote:
Originally Posted by DrCube View Post
one of the Hawaiian islands (maybe Hawaii itself) is the tallest measured from base to peak if you accept that most of it is underwater.
Yep, Mauna Kea on the Big Island.
  #14  
Old 05-22-2009, 12:00 PM
Shamozzle Shamozzle is offline
Guest
 
Join Date: Apr 2007
Posts: 2,279
Quote:
Originally Posted by pipper View Post
notfrommensa is on the right track. It's because Kili is the world's largest/ tallest freestanding mountain (that is on land anyway. I think there are some underwater volcanoes that are larger).

In other words, the difference between the summit and the surrounding land is the greatest. Everest is higher, but since the surrounding land is also very high, the absolute difference is less.
I believe Mount McKinley/Denali takes the cake in that department, with a relative vertical relief of around 5.5 km.
  #15  
Old 05-22-2009, 02:19 PM
Shoeless's Avatar
Shoeless Shoeless is offline
Charter Member
 
Join Date: Jan 2003
Location: The Sunflower State
Posts: 6,221
Also, it has been determined by geologists that Kansas really is flatter than a pancake.
  #16  
Old 05-22-2009, 02:43 PM
RickJay RickJay is online now
Charter Jays Fan
Moderator
 
Join Date: Jun 2000
Location: Oakville, Canada
Posts: 40,253
Quote:
Originally Posted by DrCube View Post
My understanding (no cite, sorry, maybe another poster will confirm) is that Everest is the highest point above sea level, Kilimanjaro is the highest mountain on land measured from the surrounding land to the peak, and that one of the Hawaiian islands (maybe Hawaii itself) is the tallest measured from base to peak if you accept that most of it is underwater.
I guess it depends where you measure from, but according to the resources I can find online, the prominence of Mount Logan (17224 feet) is quite a bit higher than Kilmanjaro (15100 feet, or possibly 16700 feet.) Spome resources also cite Mount Aconcagua as higher, and some McKinley as higher.

I can't find a really clear explanation of who's measuring from what.
  #17  
Old 05-22-2009, 02:48 PM
Drum God Drum God is offline
Charter Member
 
Join Date: Mar 2000
Location: Central Texas, USA
Posts: 2,151
Since we've established that Earth is smoother than a billiard ball, is it also dryer? If I were to shoot my Earth across the pool table, would it leave a wet trail behind? If I pick it up in my hand, will it feel bone dry, damp, moist, or like my dog just brought it to me?
  #18  
Old 05-22-2009, 02:50 PM
Sage Rat's Avatar
Sage Rat Sage Rat is offline
Member
 
Join Date: Mar 2004
Location: Howdy
Posts: 20,616
Quote:
Originally Posted by Malacandra View Post
Why Kilimanjaro, out of interest? You know, what with Everest being way higher and all that.
Poor memory
  #19  
Old 05-22-2009, 02:59 PM
Captain Carrot Captain Carrot is offline
Guest
 
Join Date: Jun 2003
Location: Sophomore at VTech
Posts: 6,039
Quote:
Originally Posted by Shoeless View Post
Also, it has been determined by geologists that Kansas really is flatter than a pancake.
That study found that a whole lot of things were flatter than a pancake, though, partly because a pancake is only flat from our perspective (lots of little bubbles from cooking), and partially because they didn't exclude enough of the edge of the pancake, so they put in a good bit of slope.
  #20  
Old 05-22-2009, 02:59 PM
Johnny L.A. Johnny L.A. is online now
Charter Member
 
Join Date: Jan 2000
Location: NoWA
Posts: 59,934
Just how smooth is the Earth?

Well, I saw it chatting up Venus once...
  #21  
Old 05-22-2009, 03:52 PM
scr4 scr4 is offline
Member
 
Join Date: Aug 1999
Location: Alabama
Posts: 15,000
Quote:
Originally Posted by Sage Rat View Post
A pool ball is maybe an inch to an inch and a half in radius. Do you think you can perceive 2.6 thousandths of an inch (6.6 hundredths of a millimeter)?
That's about the thickness of aluminum foil, or the diameter of a human hair. If the ball were out of round by this much, of course you couldn't tell. But if there was a small irregularity of this height (e.g. a scratch or small bump), I think you'd be able to tell pretty easily.

Last edited by scr4; 05-22-2009 at 03:53 PM.
  #22  
Old 05-22-2009, 04:01 PM
Sage Rat's Avatar
Sage Rat Sage Rat is offline
Member
 
Join Date: Mar 2004
Location: Howdy
Posts: 20,616
Quote:
Originally Posted by scr4 View Post
That's about the thickness of aluminum foil, or the diameter of a human hair. If the ball were out of round by this much, of course you couldn't tell. But if there was a small irregularity of this height (e.g. a scratch or small bump), I think you'd be able to tell pretty easily.
Those appear to both be about double the thickness. A hair is about a tenth of a millimeter and aluminum foil about 2 tenths. So it probably would be detectable as a scratch or whatever.

http://en.wikipedia.org/wiki/Aluminum_foil
http://wiki.answers.com/Q/What_is_th...f_a_human_hair
  #23  
Old 05-22-2009, 04:16 PM
Quartz's Avatar
Quartz Quartz is offline
Charter Member
 
Join Date: Jan 2003
Location: Home of the haggis
Posts: 29,813
Since the Earth is an oblate spheroid, perhaps a better comparison might be with a bowls ball? (NB: not bowling ball.)

Regardless, I recall reading somewhere (offline - and Google isn't helping) that the human sense of touch is sensitive to within several microns.
  #24  
Old 05-22-2009, 04:42 PM
Malacandra Malacandra is offline
BANNED
 
Join Date: Jan 2003
Location: England, Britain, UK
Posts: 18,480
Quote:
Originally Posted by RickJay View Post
Everest is still far, far under the percentage tolerance allowable in an official pool ball.
I said differently? Sure, 5 mile mountain, 4000 mile radius planet, insignificant bump - I've no disagreement there.

Otherwise I see we've had some interesting points of view put forward as to whether you measure bumpiness by height above the local mean or by distance from the centre of the spheroid, in which case Kilimanjaro's not necessarily a bad choice and Everest is not necessarily in pole position on any criterion.

And of course we've been to the top of either Everest or Kilimanjaro - or to the Moon - many times more often than we've been to the - Ow! Stop that!

Last edited by Malacandra; 05-22-2009 at 04:43 PM.
  #25  
Old 05-22-2009, 04:48 PM
Quartz's Avatar
Quartz Quartz is offline
Charter Member
 
Join Date: Jan 2003
Location: Home of the haggis
Posts: 29,813
Quote:
Originally Posted by Malacandra View Post
And of course we've been to the top of either Everest or Kilimanjaro - or to the Moon - many times more often than we've been to the - Ow! Stop that!

You're a very naughty boy; I think we'll start with the comfy chair.
  #26  
Old 05-22-2009, 05:16 PM
The Controvert The Controvert is offline
Guest
 
Join Date: Sep 2001
Location: Austin, TX
Posts: 3,763
Quote:
Originally Posted by Sage Rat View Post
Those appear to both be about double the thickness. A hair is about a tenth of a millimeter and aluminum foil about 2 tenths. So it probably would be detectable as a scratch or whatever.

http://en.wikipedia.org/wiki/Aluminum_foil
http://wiki.answers.com/Q/What_is_th...f_a_human_hair
This is closer to my mental model. I don't think the Earth is smoother than a new billiard ball, then. This would seem to suggest that it is not.
  #27  
Old 05-22-2009, 05:47 PM
Fear Itself Fear Itself is offline
Friend of Cecil
Charter Member
 
Join Date: Apr 1999
Location: Flavortown
Posts: 35,458
Quote:
Originally Posted by Quartz View Post
Since the Earth is an oblate spheroid, perhaps a better comparison might be with a bowls ball?
The equatorial bulge represents a difference of only .003 percent from the polar circumference, so while technically oblate, it is still within the tolerances of a billiard ball.

ETA: Never mind, math is not my strong point. .3 percent is more like it, so it is outside the tolerances of the billiard ball.

Last edited by Fear Itself; 05-22-2009 at 05:51 PM.
  #28  
Old 05-22-2009, 05:58 PM
Fear Itself Fear Itself is offline
Friend of Cecil
Charter Member
 
Join Date: Apr 1999
Location: Flavortown
Posts: 35,458
Quote:
Originally Posted by Fear Itself View Post
ETA: Never mind, math is not my strong point. .3 percent is more like it, so it is outside the tolerances of the billiard ball.
But not by much; after calculating the billiard ball tolerances as percent of the circumference, it turns out it is .2 percent, compared to .3 percent for the equatorial bulge of the Earth. Damn close.
  #29  
Old 05-22-2009, 06:06 PM
zut zut is offline
Charter Member
 
Join Date: Apr 2000
Location: Detroit, MI
Posts: 3,724
Quote:
Originally Posted by Sage Rat View Post
Those appear to both be about double the thickness. A hair is about a tenth of a millimeter and aluminum foil about 2 tenths. So it probably would be detectable as a scratch or whatever.

http://en.wikipedia.org/wiki/Aluminum_foil
http://wiki.answers.com/Q/What_is_th...f_a_human_hair
Aluminum foil is not, in general two tenths of a millimeter. Aluminum foil, in general, has a thickness less than two tenths of a millimeter. Household aluminum foil is in the range of .02mm, a full order of magnitude less.

As to whether you could feel features of this size on a pool ball, I think it would depend more on the steepness of the feature than the absolute height. Something like the Grand Canyon, with its steep walls, you could probably feel. Mount Everest, I don't know.

Quote:
Originally Posted by The Controvert View Post
According to this post, the smoothness of the Earth is compared to ball bearings and billiard balls.
Due respect to the Bad Astronomer, but he's wrong on this one. "Smoothness" is a measurement of surface finish, not a measurement of sphericity or deviation from a standard diameter. The specification quoted (diametral tolerance of +/- 0.005 inches) covers only the deviation from standard size. It does not, necessarily, cover how spherical the ball may be, and it *certainly* says nothing whatsoever about surface roughness.

So the Earth isn't *more* smooth than a billiard ball or a reasonably-sized ball-bearing. Whether it's close is a matter of opinion, but I'd say not really.
  #30  
Old 05-22-2009, 06:27 PM
Shalmanese Shalmanese is offline
Charter Member
 
Join Date: Feb 2001
Location: Shenzhen, China
Posts: 7,235
Quote:
Originally Posted by Drum God View Post
Since we've established that Earth is smoother than a billiard ball, is it also dryer? If I were to shoot my Earth across the pool table, would it leave a wet trail behind? If I pick it up in my hand, will it feel bone dry, damp, moist, or like my dog just brought it to me?
The total volume of water on earth is 1 360 000 000 km≥ [1] which weighs 1.36*10^21kg [2]. The mass of the earth is 5.97*10^24 kg[3] so water makes up 0.23% [5].

A billiard ball weighs 150 grams [6] so 0.23% of that is 0.034 grams[7] which is roughly equivilant to:

~ 0.4 x typical large sand grain mass (~ 9x10^-5 kg )
~ 10 x mass of a typical snowflake (~ 3x10^-6 kg )
~ 20 x mass of a typical mosquito (~ 1x10^-6 kg )
Radius r of a drop of water from m=rho 4pir^3/3:
| 2 mm (millimeters)
| (assuming water density ~~ 1000 kg/m^3)

So no, I'm betting it wouldn't leave a wet trail. There's slightly less than a single drop of water on your earth billiard ball.
  #31  
Old 05-22-2009, 08:05 PM
Drum God Drum God is offline
Charter Member
 
Join Date: Mar 2000
Location: Central Texas, USA
Posts: 2,151
Quote:
Originally Posted by Shalmanese View Post
The total volume of water on earth is 1 360 000 000 km≥ [1] which weighs 1.36*10^21kg [2]. The mass of the earth is 5.97*10^24 kg[3] so water makes up 0.23% [5].

A billiard ball weighs 150 grams [6] so 0.23% of that is 0.034 grams[7] which is roughly equivilant to:

~ 0.4 x typical large sand grain mass (~ 9x10^-5 kg )
~ 10 x mass of a typical snowflake (~ 3x10^-6 kg )
~ 20 x mass of a typical mosquito (~ 1x10^-6 kg )
Radius r of a drop of water from m=rho 4pir^3/3:
| 2 mm (millimeters)
| (assuming water density ~~ 1000 kg/m^3)

So no, I'm betting it wouldn't leave a wet trail. There's slightly less than a single drop of water on your earth billiard ball.
That sure isn't much water to get spread over three quarters of the billiard ball's surface.
  #32  
Old 05-22-2009, 09:09 PM
enalzi enalzi is offline
Guest
 
Join Date: Apr 2008
Location: Chicago, IL
Posts: 7,292
Quote:
Originally Posted by zut View Post
As to whether you could feel features of this size on a pool ball, I think it would depend more on the steepness of the feature than the absolute height. Something like the Grand Canyon, with its steep walls, you could probably feel. Mount Everest, I don't know.
I would think that even the grand canyon would be to narrow to notice.
  #33  
Old 05-22-2009, 09:40 PM
cmyk's Avatar
cmyk cmyk is offline
Member
 
Join Date: Mar 2001
Location: The Mitt
Posts: 14,221
Would it be possible, considering the highly accurate topological data of the surface of our planet we now have, thanks to satellite measurements, to take a metal sphere, machined and highly polished to the scale/dimensions of our planet (say about 2 or 3 feet in diameter?), and laser-etch that topology into the sphere's surface.

It sounds like something that would need incredibly sensitive and precise equipment and technology. I would think we could do something like that. But I wonder what materials and technologies we could use to get thoe most accurate result. I'm thinking a super hard/brittle metal like tungsten carbide or something, but I don't know. Maybe aluminum would be more than adequate.

I'd also ignore the oceans. I think it'd be far more interesting to see/feel the very sight edge of the continental shelfs, and all the other interesting things that consists of 70% of the surface.
  #34  
Old 05-22-2009, 09:48 PM
notfrommensa notfrommensa is offline
Guest
 
Join Date: Oct 2000
Posts: 11,724
I guess it is the nerd in me that I find this thread utterly fascinating.

One drop of water on a scale model of earth on a billiard ball? geez, ~70% of the earth surface is water. Considering the ocean is deep (I am not going there) that is one thin film of water on the billiard ball.
  #35  
Old 05-22-2009, 09:50 PM
zut zut is offline
Charter Member
 
Join Date: Apr 2000
Location: Detroit, MI
Posts: 3,724
Quote:
Originally Posted by enalzi View Post
I would think that even the grand canyon would be to narrow to notice.
The Grand Canyon ranges from 4-18 miles across. At pool ball scale, that's about 0.001" to 0.005" -- in the range of the thickness of a piece of paper, and definitely something you could catch the edge of your fingernail on.
  #36  
Old 05-23-2009, 05:36 PM
Ximenean Ximenean is offline
Guest
 
Join Date: Aug 2001
Posts: 7,112
Quote:
Originally Posted by Shalmanese View Post
The total volume of water on earth is 1 360 000 000 km≥ [1] which weighs 1.36*10^21kg [2]. The mass of the earth is 5.97*10^24 kg[3] so water makes up 0.23% [5].

A billiard ball weighs 150 grams [6] so 0.23% of that is 0.034 grams[7] which is roughly equivilant to:

~ 0.4 x typical large sand grain mass (~ 9x10^-5 kg )
~ 10 x mass of a typical snowflake (~ 3x10^-6 kg )
~ 20 x mass of a typical mosquito (~ 1x10^-6 kg )
Radius r of a drop of water from m=rho 4pir^3/3:
| 2 mm (millimeters)
| (assuming water density ~~ 1000 kg/m^3)

So no, I'm betting it wouldn't leave a wet trail. There's slightly less than a single drop of water on your earth billiard ball.
I think you're a factor of ten out there. I make it that water is 0.023% of the total mass of the Earth.

It is startling, how thin the layer of water on the Earth's surface is. For something that affects the climate and the biology so much to be little more than a film of water on the surface.

It always seems fortuitous to me that there is just the right amount of water on the Earth. Not enough to make the planet a Waterworld, but enough so that the place is not an arid desert punctuated by the occasional lake. Maybe it's an example of the anthropic principle. I doubt that desert planets have much going for them, but could civilisation have arisen on a planet entirely covered by water?
(Kevin Costner notwithstanding.)
  #37  
Old 05-23-2009, 10:14 PM
Sage Rat's Avatar
Sage Rat Sage Rat is offline
Member
 
Join Date: Mar 2004
Location: Howdy
Posts: 20,616
Though I suspect that the bigger issue would be whether the Earth, shrunk down to the size of a billiard ball and subjected to the gravitational pull of a full sized Earth, could survive without falling apart and leaking molten goo all over the place.
  #38  
Old 05-24-2009, 12:19 PM
DesertDog DesertDog is online now
Charter Member
 
Join Date: Oct 2002
Location: Mesa, Ariz.
Posts: 4,581
We hashed all this out in a thread I killed about six weeks ago.
  #39  
Old 05-24-2009, 02:10 PM
Sunspace Sunspace is offline
Member
 
Join Date: Jun 1999
Location: Near the GT eeehhhh...
Posts: 27,622
Quote:
Originally Posted by Shoeless View Post
Also, it has been determined by geologists that Kansas really is flatter than a pancake.
Depends on which pancake we're talking about, doesn't it? The pancake in the linked article doesn't look like a standard 'pour the batter in the pan'-type pancake; it looks more folded than layered (metamorphic rather than sedimantary).
Quote:
Originally Posted by Quartz View Post
You're a very naughty boy; I think we'll start with the comfy chair.
:: ears perk up with interest ::
Quote:
Originally Posted by Sage Rat View Post
Though I suspect that the bigger issue would be whether the Earth, shrunk down to the size of a billiard ball and subjected to the gravitational pull of a full sized Earth, could survive without falling apart and leaking molten goo all over the place.
So are we talking 'rotten kiwifruit left on the kitchen counter for three days' or 'raw egg' or 'cream-filled chocolate egg' or what?

Last edited by Sunspace; 05-24-2009 at 02:10 PM.
Reply

Bookmarks

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is Off
HTML code is Off

Forum Jump


All times are GMT -5. The time now is 03:28 PM.

Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2018, vBulletin Solutions, Inc.

Send questions for Cecil Adams to: cecil@straightdope.com

Send comments about this website to: webmaster@straightdope.com

Terms of Use / Privacy Policy

Advertise on the Straight Dope!
(Your direct line to thousands of the smartest, hippest people on the planet, plus a few total dipsticks.)

Copyright © 2018 STM Reader, LLC.

 
Copyright © 2017