How much less does the earth weigh now?
January 14, 2011 8:18 PM Subscribe
How much less does the earth weigh now?
Many of the resources that are found in the earth are turned into gases as they are consumed. Clearly mining and similar has been going on for ages. How much less does the earth weigh now compared to, say 1000 years ago?
Many of the resources that are found in the earth are turned into gases as they are consumed. Clearly mining and similar has been going on for ages. How much less does the earth weigh now compared to, say 1000 years ago?
Best answer: It weighs the same. Gasses have weight also and most nutrients cycle.
See here.
And here.
posted by cnanderson at 8:26 PM on January 14, 2011
See here.
And here.
posted by cnanderson at 8:26 PM on January 14, 2011
I should add, though, that even over the Earth's lifetime that additional mass 'only' adds to up about 8 x 1013 kg. That's roughly .000000001% of the Earth's total mass. So while on the one hand it's vastly more than we've lost in the way of escaping gases, satellites, and space probes, it's still only an extremely small fraction of the Earth as a whole.
posted by jedicus at 8:33 PM on January 14, 2011 [1 favorite]
posted by jedicus at 8:33 PM on January 14, 2011 [1 favorite]
If the earth weighs any less, it's because of the probes we've sent into space, not because of fossil fuels burning into gasses. Even though it's liquid turning into gas, the component atoms will have the same mass; they're just combined differently.
But, as jedicus points out, space debris constantly gets added to earth's mass, and if I remember my high school physics class right "mass" is the right term rather than "weight," because one refers to matter and the other gravity.
posted by Rinku at 8:35 PM on January 14, 2011
But, as jedicus points out, space debris constantly gets added to earth's mass, and if I remember my high school physics class right "mass" is the right term rather than "weight," because one refers to matter and the other gravity.
posted by Rinku at 8:35 PM on January 14, 2011
Response by poster: Interesting links, thank you.
I am surprised that that more gas doesn't leak into space. I also thought that the amount of energy lost as heat would be significant making the earth an open system.
posted by dantodd at 8:36 PM on January 14, 2011
I am surprised that that more gas doesn't leak into space. I also thought that the amount of energy lost as heat would be significant making the earth an open system.
posted by dantodd at 8:36 PM on January 14, 2011
I am surprised that that more gas doesn't leak into space.
There's nothing keeping gases near the earth other than gravity, and the only reason the earth has an atmosphere while the moon doesn't is because it's bigger, and thus has enough gravitational attraction to maintain an atmosphere. There's nothing to leak from, and nothing for gases to really escape to.
posted by LionIndex at 9:13 PM on January 14, 2011
There's nothing keeping gases near the earth other than gravity, and the only reason the earth has an atmosphere while the moon doesn't is because it's bigger, and thus has enough gravitational attraction to maintain an atmosphere. There's nothing to leak from, and nothing for gases to really escape to.
posted by LionIndex at 9:13 PM on January 14, 2011
How do you plan to lose heat to a vacuum?
Radiatively.
posted by fatllama at 9:25 PM on January 14, 2011 [5 favorites]
Radiatively.
posted by fatllama at 9:25 PM on January 14, 2011 [5 favorites]
How do you plan to lose heat to a vacuum?
By radiation.
posted by It's Never Lurgi at 9:26 PM on January 14, 2011
By radiation.
posted by It's Never Lurgi at 9:26 PM on January 14, 2011
LionIndex - lightweight molecules at the high tail of the temperature spectrum can reach Earth's escape velocity, and are lost to space. However, the mass loss is ~94672800kg per year¹, which is on the order of 2*10^-16 of the Earth's mass - that's absolutely negligible.
I also thought that the amount of energy lost as heat would be significant
I have no idea how much energy the Earth radiates as heat, but given the c² term in E=mc² the mass equivalence will be very, very small.
1. The loss rate is currently tiny, only about three kilograms of hydrogen and 50 grams of helium (the two lightest gases) per second
posted by russm at 9:41 PM on January 14, 2011 [1 favorite]
I also thought that the amount of energy lost as heat would be significant
I have no idea how much energy the Earth radiates as heat, but given the c² term in E=mc² the mass equivalence will be very, very small.
1. The loss rate is currently tiny, only about three kilograms of hydrogen and 50 grams of helium (the two lightest gases) per second
posted by russm at 9:41 PM on January 14, 2011 [1 favorite]
Best answer: Which gaseous molecule escapes from the atmosphere and which is contained depends on a number of factors: temperature (how fast the molecules are moving), gravity (how much force pulling it back) and mass of the atom. This webpage explain your question quite well:
http://abyss.uoregon.edu/~js/ast121/lectures/lec14.html
You are confused between energy and mass. Energy has no mass (E=mc^2 -> m=E/c^2, but c is a very large number, m is effectively 0). The Earth absorb energy from the Sun (sunlight) and it also radiates energy out to space (heat). The balance of those source and drain determine the average temperature of the Earth atmosphere. Green house gas, loss of highly reflective snow cover, cloud cover... etc all effect that balance in a complex interaction. I suppose if Earth's atmosphere trap heat so effectively via the green house effect, we might start loosing some H2O; but there are too many factors to tell.
posted by curiousZ at 9:45 PM on January 14, 2011
http://abyss.uoregon.edu/~js/ast121/lectures/lec14.html
You are confused between energy and mass. Energy has no mass (E=mc^2 -> m=E/c^2, but c is a very large number, m is effectively 0). The Earth absorb energy from the Sun (sunlight) and it also radiates energy out to space (heat). The balance of those source and drain determine the average temperature of the Earth atmosphere. Green house gas, loss of highly reflective snow cover, cloud cover... etc all effect that balance in a complex interaction. I suppose if Earth's atmosphere trap heat so effectively via the green house effect, we might start loosing some H2O; but there are too many factors to tell.
posted by curiousZ at 9:45 PM on January 14, 2011
The number of humans on Earth has increased by about 6 billion in the past 1000 years - at an average of 150 pounds per human, wouldn't that add up to about 900 billion more pounds?
posted by kbar1 at 10:45 PM on January 14, 2011
posted by kbar1 at 10:45 PM on January 14, 2011
More people consume more resources, kbar. Plus and minus.
posted by rokusan at 10:52 PM on January 14, 2011
posted by rokusan at 10:52 PM on January 14, 2011
Response by poster: Thank you all. I think the question has been answered.
Just to be clear, I referred to the earth being an open system in the sense that I wasn't convinced that energy and/or matter would have to be conserved.
Thanks again for the interesting answers.
posted by dantodd at 11:18 PM on January 14, 2011
Just to be clear, I referred to the earth being an open system in the sense that I wasn't convinced that energy and/or matter would have to be conserved.
Thanks again for the interesting answers.
posted by dantodd at 11:18 PM on January 14, 2011
wouldn't that add up to about 900 billion more pounds?
Well, a) that flesh was created from consuming nutrients and water that already existed, it didn't just suddenly spring into existence from nowhere. Mass can be neither created nor destroyed, except in a nuclear reaction. And b) even if it was, it would only represent 0.0000000000068% of the mass of the Earth.
posted by Rhomboid at 11:22 PM on January 14, 2011 [1 favorite]
Well, a) that flesh was created from consuming nutrients and water that already existed, it didn't just suddenly spring into existence from nowhere. Mass can be neither created nor destroyed, except in a nuclear reaction. And b) even if it was, it would only represent 0.0000000000068% of the mass of the Earth.
posted by Rhomboid at 11:22 PM on January 14, 2011 [1 favorite]
The number of humans on Earth has increased by about 6 billion in the past 1000 years - at an average of 150 pounds per human, wouldn't that add up to about 900 billion more pounds?
Nonliving matter on the earth became living matter. When people die it once again becomes nonliving matter. The form changes but the mass is constant.
More people consume more resources, kbar. Plus and minus.
And so it is, in turn, with the natural resources they consume. "consumption" changes the form and location, but the mass is the same.
There's only one thing humans do which genuinely consumes mass: nuclear power (including nuclear weapons). The Hiroshima bomb transformed a bit less than a gram of mass into energy, and subsequent nuclear weapons, plus nuclear power plants all over the world, have been turning mass into energy ever since.
But the total quantity of mass converted at this point is much less than a ton, and it's in the noise when compared to the amount of new mass the planet picks up from meteors each year.
posted by Chocolate Pickle at 12:13 AM on January 15, 2011
Nonliving matter on the earth became living matter. When people die it once again becomes nonliving matter. The form changes but the mass is constant.
More people consume more resources, kbar. Plus and minus.
And so it is, in turn, with the natural resources they consume. "consumption" changes the form and location, but the mass is the same.
There's only one thing humans do which genuinely consumes mass: nuclear power (including nuclear weapons). The Hiroshima bomb transformed a bit less than a gram of mass into energy, and subsequent nuclear weapons, plus nuclear power plants all over the world, have been turning mass into energy ever since.
But the total quantity of mass converted at this point is much less than a ton, and it's in the noise when compared to the amount of new mass the planet picks up from meteors each year.
posted by Chocolate Pickle at 12:13 AM on January 15, 2011
Hm. Actually the Earth probably does lose some amount of mass via radiation. Since the temperature is pretty much constant, mostly the heat radiated to space should be balanced by insolation, but there is one major non-solar heat source on the planet, which is radioactive decay: this is what keeps the core molten (fossil heat from the planet's formation only accounts for about 20% of the core's heat, according to Wikipedia). WP further says that decay is producing about 30 TW, which would amount to about one kilogram per hour of mass— much smaller than the loss rate of light elements from the upper atmosphere (by about four orders of magnitude).
posted by hattifattener at 1:08 AM on January 15, 2011
posted by hattifattener at 1:08 AM on January 15, 2011
Just to be pedantic, I think you're talking about mass rather than weight. The Earth weighs precisely nothing.
posted by Nick Jordan at 4:27 AM on January 15, 2011 [3 favorites]
posted by Nick Jordan at 4:27 AM on January 15, 2011 [3 favorites]
How do you plan to lose heat to a vacuum?
*points at 2 x 10^30 kg ball of burning gas about 8 light minutes away*
How did you think heat got from there to here?
posted by obiwanwasabi at 4:47 AM on January 15, 2011 [4 favorites]
*points at 2 x 10^30 kg ball of burning gas about 8 light minutes away*
How did you think heat got from there to here?
posted by obiwanwasabi at 4:47 AM on January 15, 2011 [4 favorites]
obiwanwasabi - the solar wind consists of particles of phlogiston liberated in the Sun's combustion, that then react with the Earth's atmosphere producing heat?
posted by russm at 5:20 PM on January 18, 2011
posted by russm at 5:20 PM on January 18, 2011
I believe that the overall mass of the Earth is rising, due to meteors etc, but it would be interesting to know how much mass is being converted to energy by radioactive decay of uranium and thorium in the Earth's core.
posted by Chocolate Pickle at 10:45 PM on January 20, 2011
posted by Chocolate Pickle at 10:45 PM on January 20, 2011
This thread is closed to new comments.
posted by jedicus at 8:25 PM on January 14, 2011 [1 favorite]