# Is the Earth gaining weight? **URL:** \ **Category:** Factual Questions\ **Created:** [March 31, 2006, 2:53pm UTC](https://boards.straightdope.com/t/is-the-earth-gaining-weight/350698 "2006-03-31T14:53:52Z")\ **Posts on this page:** 20\ **Page:** 1
**Author:** ![Uncommon\_Sense](https://avatars.discourse-cdn.com/v4/letter/u/f9ae1b/32.png) [@Uncommon\_Sense](https://boards.straightdope.com/u/Uncommon_Sense)\ **Post date:** [March 31, 2006, 2:53pm UTC](https://boards.straightdope.com/t/is-the-earth-gaining-weight/350698/1 "2006-03-31T14:53:52Z")
By absorbing energy from the sun? Plants/animals then change that energy into matter (kind of). If it does add mass to the Earth can this be measured? ---
**Author:** ![CookingWithGas](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/cookingwithgas/32/485_2.png) [@CookingWithGas](https://boards.straightdope.com/u/CookingWithGas)\ **Post date:** [March 31, 2006, 3:03pm UTC](https://boards.straightdope.com/t/is-the-earth-gaining-weight/350698/2 "2006-03-31T15:03:21Z")
In some sense the Earth is gaining mass due to the energy from the sun, due to energy/mass equivalence. I don’t know enough to give you the formula and estimate it. It can’t be measured in a direct sense (i.e., weigh Earth) of course, but you could estimate fairly accurately if you knew how much energy from the sun falls on the earth’s surface at what rate. My guess would be that weight gain due to cosmic dust is probably greater, [“. . .probably on the order of 40 +/- 20 thousand tons per year”](http://www.cnn.com/2005/TECH/space/08/29/cosmic.dust/index.html). ---
**Author:** ![AskNott](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/asknott/32/5790_2.png) [@AskNott](https://boards.straightdope.com/u/AskNott)\ **Post date:** [March 31, 2006, 3:17pm UTC](https://boards.straightdope.com/t/is-the-earth-gaining-weight/350698/3 "2006-03-31T15:17:58Z")
I’ll try to remember that when I think about my house being dusty. It’s all that dang cosmic dust. ---
**Author:** ![Procyon](https://avatars.discourse-cdn.com/v4/letter/p/ac91a4/32.png) [@Procyon](https://boards.straightdope.com/u/Procyon)\ **Post date:** [March 31, 2006, 3:23pm UTC](https://boards.straightdope.com/t/is-the-earth-gaining-weight/350698/4 "2006-03-31T15:23:13Z")
You pose a very interesting question. I am not exactly sure how you’d figure out how much mass could be gained from sunlight, but I can tell you how to find the total amount of energy per unit time that the Earth receives from the sun. Some numbers: Solar constant (S) = 1370 W m[SUP]-2[/SUP] Radius of the earth ® = 6.4 \* 10[SUP]5[/SUP] m Cross-sectional area of the earth (A) = pi\*r[SUP]2[/SUP] = 1.3 \* 10[SUP]14[/SUP] m[SUP]2[/SUP] Total energy received by the Earth from the sun is given by S \* A: S \* A = 1.8 \* 10[SUP]17[/SUP] Watts How much of this energy can be converted into mass (and by what processes) I do not know. The more I think about photosynthesis, the less I feel like I understand it. I would love to be enlightened, excuse the pun, on this matter. ---
**Author:** ![Bryan\_Ekers](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/bryan_ekers/32/183_2.png) [@Bryan\_Ekers](https://boards.straightdope.com/u/Bryan_Ekers)\ **Post date:** [March 31, 2006, 3:35pm UTC](https://boards.straightdope.com/t/is-the-earth-gaining-weight/350698/5 "2006-03-31T15:35:24Z")
Solar energy doesn’t bring about an increase in mass; it’s more like a welding torch. The energy allows plants to combine and break apart elements they couldn’t normally, just as welding together two 50lb blocks requires a torch, but the end result is still just 100lbs. ---
**Author:** ![Exapno\_Mapcase](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/exapno_mapcase/32/1051_2.png) [@Exapno\_Mapcase](https://boards.straightdope.com/u/Exapno_Mapcase)\ **Post date:** [March 31, 2006, 3:40pm UTC](https://boards.straightdope.com/t/is-the-earth-gaining-weight/350698/6 "2006-03-31T15:40:56Z")
Photosynthesis is a chemical process so it does not change matter into energy. And the earth also radiates away much of the sun’s incoming energy as outgoing heat, light, and long-wave radiation. The presumption is that incoming energy must approximately balance outgoing radiation or else we would see major warming or coooling trends on earth. Some scientists do say that this is exactly what is happening, to be sure. However, the unbalance must be tiny compared to the total amount of heat received or else conditions would change more rapidly and more extremely than they are. Here’s how the breakdown works: [Heating in the Atmosphere](http://www.newton.dep.anl.gov/askasci/wea00/wea00082.htm) > [@](#): > > First, we must assume that there is in fact a “balance”…i.e., that the > heat gain and loss from both the earth and atmosphere equals out over time. > Otherwise, the earth would be warming or cooling (which in fact may very > well be happening), but we will assume that there is a zero balance from > incoming and outgoing radiation. It would be much easier explained if I > could use a diagram or graphic, to draw the respective radiation exchanges, > but I’ll try to use a table, similiar to a auditor or bookkeeper’s journal, > such that the income and outgo balance. I’ll detail the heat gains at the > earth, and the heat losses from the earth, and then the heat gains to the > atmosphere, and the heat losses from the atmosphere. > > Earth Heat Gains > short-wave radiation from the sun…34.7% > long-wave radiation from the atmosphere…65.3% > > Earth Heat Losses > Long-wave radiation to the atmosphere…75.5% > Long-wave radiation to space… 4.1% > Evaporation from oceans/lakes/land…15.6% > Convection and conduction to atmosphere… 4.8% > > Atmospheric Heat Gains > Short-wave radiation from the sun…11.9% > Heat to atmosphere from condensation…14.4% > Heat to atmosphere from convection/conduction… 4.4% > Long-wave radiation from earth…69.4% > > Atmospheric Heat Losses > Long-wave radiation Radiated to Space…40.0% > Long-wave radiation radiated to earth…60.0% > > These values derived from graphs and charts from the textbook “Meterorology > Today,” (4th Ed.) by C. Donald Ahrens. > > This is a greatly simplified summary of the radiation balance. Each of the > above factors involve other effects, such as albedo, solar angle, selective > absorption of radiation by atmospheric gases such as carbon dioxide, ozone, > water vapor, et.al., scattering and reflection of solar radiation, etc. Probably, however, the earth’s mass is more affected by the gradual acumlation of micrometeor dust than by anything from the sun. For comparison, take the estimated [100 tonnes](http://www.irf.se/Meteoroids2001/program/Session5.html) of inter-planetary dust that enters the atmosphere each day. ---
**Author:** ![Malacandra](https://avatars.discourse-cdn.com/v4/letter/m/45deac/32.png) [@Malacandra](https://boards.straightdope.com/u/Malacandra)\ **Post date:** [March 31, 2006, 3:44pm UTC](https://boards.straightdope.com/t/is-the-earth-gaining-weight/350698/7 "2006-03-31T15:44:12Z")
> [@Procyon](#): > > You pose a very interesting question. > > I am not exactly sure how you’d figure out how much mass could be gained from sunlight, but I can tell you how to find the total amount of energy per unit time that the Earth receives from the sun. > > Some numbers: > > Solar constant (S) = 1370 W m[SUP]-2[/SUP] > Radius of the earth (r) = 6.4 \* 10[SUP]5[/SUP] m > Cross-sectional area of the earth (A) = pi\*r[SUP]2[/SUP] = 1.3 \* 10[SUP]14[/SUP] m[SUP]2[/SUP] > > Total energy received by the Earth from the sun is given by S \* A: > > S \* A = 1.8 \* 10[SUP]17[/SUP] Watts > > How much of this energy can be converted into mass (and by what processes) I do not know. The more I think about photosynthesis, the less I feel like I understand it. I would love to be enlightened, excuse the pun, on this matter. Photosynthesis? Roughly speaking, it’s a case of 6H[sub]2[/sub]O and 6CO[sub]2[/sub] = C[sub]6[/sub]H[sub]12[/sub]O[sub]6[/sub] and 6O[sub]2[/sub]. The conversion works perfectly well in one direction, releasing energy (burning sugar), so all you need to make it go the other way is an energy _input_ and some kind of conversion matrix, which is what chlorophyll is. ---
**Author:** ![ElvisL1ves](https://avatars.discourse-cdn.com/v4/letter/e/5daacb/32.png) [@ElvisL1ves](https://boards.straightdope.com/u/ElvisL1ves)\ **Post date:** [March 31, 2006, 3:55pm UTC](https://boards.straightdope.com/t/is-the-earth-gaining-weight/350698/8 "2006-03-31T15:55:12Z")
[This may not be the best cite](http://www.talkorigins.org/faqs/moon-dust.html), but it points out that the Earth is constantly attracting mass from bombardment by meteorites. The table listing various estimates ranges from 1600 to 15,000 metric tonnes per year. It doesn’t AFAICT account for losses from the Earth, such as from high-altitude air molecules reaching escape velocity, and so forth. ---
**Author:** ![Stranger\_On\_A\_Train](https://avatars.discourse-cdn.com/v4/letter/s/13edae/32.png) [@Stranger\_On\_A\_Train](https://boards.straightdope.com/u/Stranger_On_A_Train)\ **Post date:** [March 31, 2006, 4:31pm UTC](https://boards.straightdope.com/t/is-the-earth-gaining-weight/350698/9 "2006-03-31T16:31:44Z")
First of all, plants do not “change energy into mass”; they use incoming solar radiation–typically at the peaks around 460nm and 650nm–to provide energy for the chlorophyll cycle (a counterpart to the citric acid or Krebs cycle in animals which falls under the general moniker of [photosynthesis](http://io.uwinnipeg.ca/~simmons/cm1503/photosynthesis.htm)), which pumps electrons up to higher energy levels in order to create ATP which is then used to power the sythesis of carbohydrates and proteins via various secondary reactions. Aside from the rare stray neutron being captured and stimulating decay, there’s no change in mass; just change in electron/ion energies. Second, the Earth has an overall net energy absorption/radiation rate of zero, or virtually so. This is a good thing considering that the Earth receives 4.4x10[sup]16[/sup] watts of energy in the form of (mostly) visible and infrared wavelengths. Except for radiation which is directly reflected into space by highly albedic cloud cover, most radiation is absorb and reradiatated at longer (visible) wavelengths. In the case of energy stored via photosynthesis, it is reradiated after the vegetable matter is oxidized in some fashion (burned, rotted, consumed by animals, et cetera). In addition, the Earth produces a modest amount of its own radiation via radioactive decay in the core, most of which drives the core rotation that creates the magnetosphere and convection processes that drive plate tectonics. Most of this energy, too, is lost via some nonconservative process and eventually radiated as heat or momentum transfer to incoming charged particles. See [this](http://earthobservatory.nasa.gov/Newsroom/MediaResources/Energy_Balance.pdf) page (warning: PDF) for more information on the Earth’s energy balance. The Earth loses some amount of mass in terms of lost gases–primarily lightweight elements like hydrogen and helium–but also gains free atoms that get captured by gravity in addition to being bombarded by thousands of tons of meteorites and “space dust” every year. The net is a definite, although imperceivable increase in mass. So yes, the Earth is gaining weight, but not because it’s out in the limelight, but rather, like the rest of us, because it can’t pass through its daily routine without consuming a lot of extra junk. Stranger ---
**Author:** ![Uncommon\_Sense](https://avatars.discourse-cdn.com/v4/letter/u/f9ae1b/32.png) [@Uncommon\_Sense](https://boards.straightdope.com/u/Uncommon_Sense)\ **Post date:** [March 31, 2006, 6:24pm UTC](https://boards.straightdope.com/t/is-the-earth-gaining-weight/350698/10 "2006-03-31T18:24:54Z")
Is the sun loosing mass, if so where is that mass going? ---
**Author:** ![Stranger\_On\_A\_Train](https://avatars.discourse-cdn.com/v4/letter/s/13edae/32.png) [@Stranger\_On\_A\_Train](https://boards.straightdope.com/u/Stranger_On_A_Train)\ **Post date:** [March 31, 2006, 7:48pm UTC](https://boards.straightdope.com/t/is-the-earth-gaining-weight/350698/11 "2006-03-31T19:48:30Z")
> [@Uncommon Sense](#): > > Is the sun loosing mass, if so where is that mass going? Yes, [the Sun is losing mass](http://farside.ph.utexas.edu/teaching/plasma/lectures/node68.html). No, you dn’t need to worry about it. When it loses enough mass (or rather, when it converts too much of it to helium), it’ll flash and start losing matter rapidly. This will, if you are so unfortunate, undeveloped, or just idiotic to be around, ruin your entire day. Stranger ---
**Author:** ![UncleBeer](https://avatars.discourse-cdn.com/v4/letter/u/977dab/32.png) [@UncleBeer](https://boards.straightdope.com/u/UncleBeer)\ **Post date:** [March 31, 2006, 8:42pm UTC](https://boards.straightdope.com/t/is-the-earth-gaining-weight/350698/12 "2006-03-31T20:42:38Z")
Cecil: [http://www.straightdope.com/classics/a3\_355.html](http://www.straightdope.com/classics/a3_355.html) ---
**Author:** ![Uncommon\_Sense](https://avatars.discourse-cdn.com/v4/letter/u/f9ae1b/32.png) [@Uncommon\_Sense](https://boards.straightdope.com/u/Uncommon_Sense)\ **Post date:** [March 31, 2006, 9:07pm UTC](https://boards.straightdope.com/t/is-the-earth-gaining-weight/350698/13 "2006-03-31T21:07:53Z")
> [@Stranger On A Train](#): > > Yes, [the Sun is losing mass](http://farside.ph.utexas.edu/teaching/plasma/lectures/node68.html). > Stranger Silly human. You think you can fool me with your complex azymuthal asymptotes. I think you know where I’m headed, yet you continue to dodge the obvious. When will the Sun’s mass get small enough and the Earth’s mass get large enough that the Earth will simply fling itself out of it’s orbit and into the darkness of space. Huh? 😃 Really, Shouldn’t this happen before the Sun explodes? ---
**Author:** ![Ring](https://avatars.discourse-cdn.com/v4/letter/r/6a8cbe/32.png) [@Ring](https://boards.straightdope.com/u/Ring)\ **Post date:** [March 31, 2006, 9:24pm UTC](https://boards.straightdope.com/t/is-the-earth-gaining-weight/350698/14 "2006-03-31T21:24:39Z")
> [@](#): > > Photosynthesis is a chemical process so it does not change matter into energy. Actually that’s not true. If you ascribe to the whole “mass into energy” falsity then chemical processes, just like nuclear processes, do convert mass into energy. The first lowers the potential energy of the nucleus and the second lowers the potential energy of the atom / molecule. Given that m[sup]2[/sup] = E[sup]2[/sup] - p[sup]2 [/sup] ( c = 1) if the potential energy decreases so does the mass. ---
**Author:** ![Ring](https://avatars.discourse-cdn.com/v4/letter/r/6a8cbe/32.png) [@Ring](https://boards.straightdope.com/u/Ring)\ **Post date:** [March 31, 2006, 9:34pm UTC](https://boards.straightdope.com/t/is-the-earth-gaining-weight/350698/15 "2006-03-31T21:34:04Z")
> [@Ring](#): > > The first lowers the potential energy of the nucleus and the second lowers the potential energy of the atom / molecule. Given that m[sup]2[/sup] = E[sup]2[/sup] - p[sup]2 [/sup] ( c = 1) if the potential energy decreases so does the mass. Sorry that should say just the opposite. The second lowers the potential energy of the nucleus and the first lowers the potential energy of the atom / molecule. Given that m[sup]2[/sup] = E[sup]2[/sup] - p[sup]2 [/sup] ( c = 1) if the potential energy decreases so does the mass. ---
**Author:** ![Chronos](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/chronos/32/134_2.png) [@Chronos](https://boards.straightdope.com/u/Chronos)\ **Post date:** [March 31, 2006, 9:35pm UTC](https://boards.straightdope.com/t/is-the-earth-gaining-weight/350698/16 "2006-03-31T21:35:39Z")
Chemical reactions do in fact convert matter to energy, and vice versa, in just the same way that nuclear reactions do. They just do it on a much smaller scale. For that matter, if you take a lump of matter (like the Earth) in the middle of space and just heat it up, it’s gaining mass. However, the Earth radiates away essentially all of the energy it receives from the Sun, and even if it didn’t, radiant light is a very inefficient way to transfer mass, so it’d still be negligible. The Sun’s mass loss is not quite so negligible, since it’s radiating energy in all directions, only a very small fraction of which hits the Earth, and it’s not in equilibrium, since it has nothing supplying new energy to it. Even so, over its entire lifespan, the Sun will lose less than a tenth of a percent of its total mass in this way. ---
**Author:** ![Stranger\_On\_A\_Train](https://avatars.discourse-cdn.com/v4/letter/s/13edae/32.png) [@Stranger\_On\_A\_Train](https://boards.straightdope.com/u/Stranger_On_A_Train)\ **Post date:** [March 31, 2006, 9:35pm UTC](https://boards.straightdope.com/t/is-the-earth-gaining-weight/350698/17 "2006-03-31T21:35:52Z")
> [@Uncommon Sense](#): > > I think you know where I’m headed, yet you continue to dodge the obvious. > When will the Sun’s mass get small enough and the Earth’s mass get large enough that the Earth will simply fling itself out of it’s orbit and into the darkness of space. Huh? > > 😃 > > Really, > Shouldn’t this happen before the Sun explodes? Nope. After helium flash, the Sun will continue to burn up or blow off much of the light mass elements (hydrogen, helium, lithium) but the total mass loss before then isn’t enough to significantly affect orbits. The Sun is big–really, really big–and the amount of material it loses is quite small. For much larger stars–those over what is called the [Chandrasekhar limit](http://en.wikipedia.org/wiki/Chandrasekhar_limit), they’ll spontaneously blow much of their mass away in a spectacular detonation, but low mass stars on the main sequence will continue to fret about, slowly falling of the sequence by gently blowing their mass into a cotton candy envelope called a planetary nebula. Long before that happens, you’re going to have to worry about your atmosphere leaking away, your pipes freezing up, and your 401(k) being suddenly devalued owing to the rapid and completely unexpected failure of the world economy. Better make some reservations with the local WestArm Hyperspacelines office now before tickets get sold out. Stranger ---
**Author:** ![Stranger\_On\_A\_Train](https://avatars.discourse-cdn.com/v4/letter/s/13edae/32.png) [@Stranger\_On\_A\_Train](https://boards.straightdope.com/u/Stranger_On_A_Train)\ **Post date:** [March 31, 2006, 11:41pm UTC](https://boards.straightdope.com/t/is-the-earth-gaining-weight/350698/18 "2006-03-31T23:41:37Z")
> [@Chronos](#): > > Chemical reactions do in fact convert matter to energy, and vice versa, in just the same way that nuclear reactions do. They just do it on a much smaller scale. For that matter, if you take a lump of matter (like the Earth) in the middle of space and just heat it up, it’s gaining mass. However, the Earth radiates away essentially all of the energy it receives from the Sun, and even if it didn’t, radiant light is a very inefficient way to transfer mass, so it’d still be negligible. Errr…well, a lump of matter that’s heated up will have more momentum–to a point that it’ll come flying apart if you heat it up too much–but the number or mass of the fundamental particles that make it up don’t change. The net effect on the Earth is that an infinitesmal change in momentum (or, if you like, virtual mass) occurs, owing to the reradiation (in some form) of energy. E=mc[sup]2[/sup] leads to some ticklish distictions between mass and energy. I prefer to think of mass in terms of the energy that is tied up in fundamental particles, and all other forms of mass as being artifacts of momentum. As for what’s really going on with the man behind the curtain…well, you can spend a lot of sleepless nights trying to puzzle that one out. Stranger ---
**Author:** ![Ring](https://avatars.discourse-cdn.com/v4/letter/r/6a8cbe/32.png) [@Ring](https://boards.straightdope.com/u/Ring)\ **Post date:** [April 1, 2006, 1:16am UTC](https://boards.straightdope.com/t/is-the-earth-gaining-weight/350698/19 "2006-04-01T01:16:27Z")
> [@Stranger On A Train](#): > > Errr…well, a lump of matter that’s heated up will have more momentum–to a point that it’ll come flying apart if you heat it up too much–but the number or mass of the fundamental particles that make it up don’t change. The net effect on the Earth is that an infinitesmal change in momentum (or, if you like, virtual mass) occurs, owing to the reradiation (in some form) of energy. > > E=mc[sup]2[/sup] leads to some ticklish distictions between mass and energy. I prefer to think of mass in terms of the energy that is tied up in fundamental particles, and all other forms of mass as being artifacts of momentum. As for what’s really going on with the man behind the curtain…well, you can spend a lot of sleepless nights trying to puzzle that one out. > > Stranger The relativisticly correct equation for energy/mass/momentum is: E[sup]2[/sup] = m[sup]2[/sup] + p[sup]2[/sup] (c = 1) So, any time you have an energetic system of particles that have a center of momentum frame the system has mass. As you heat an object the kinetic energy of the constituent particles increases, and since these particles have a zero momentum frame the object has gained mass. m[sup]2[/sup] = E[sup]2[/sup] - 0[sup]2[/sup] ---
**Author:** ![spingears](https://avatars.discourse-cdn.com/v4/letter/s/ebca7d/32.png) [@spingears](https://boards.straightdope.com/u/spingears)\ **Post date:** [April 1, 2006, 4:45am UTC](https://boards.straightdope.com/t/is-the-earth-gaining-weight/350698/20 "2006-04-01T04:45:29Z")
> [@](#): > > Is the Earth gaining weight? YES IIRC it is on the order of tons per year. You will have to consult an astronomer for factual data. > [@Uncommon Sense](#): > > By absorbing energy from the sun?Plants/animals then change that energy into matter (kind of). If it does add mass to the Earth can this be measured? Not much. Someone else may supply that estimate! [Next page](https://boards.straightdope.com/t/is-the-earth-gaining-weight/350698.md?page=2)