Mass of the Earth

Do you mean before or after the Earth was hit by a massive object which forced the ejection of a massive amount of material which became the moon? Obviously it would weigh less if you consider "started to exist" as before the moon ejection so I'll assume you want to know from after that point. I'll say right off I don't know for sure but if you consider the Earth has gravity then it would tend to draw things into it like meteors, comets etc. which would increase mass. The only way for the Earth to lose mass is from gas particles that somehow (solar radiation? the Earth's own internal heat?) get enough energy reach escape velocity of ~25,000 mph, and of course the space vehicles that man sends up. So balancing the 2 my guess is the Earth's weighs more? Why do you want to know? Did I just do your homework for you?

I am just wondering. considerthis.We burn a lot of fossile fuel that turn into gas that is lighter than solids and liquids.We Destroyed woods and burn it,people are born and live longer now so there are a lot more people on earth now than then etc.

Ever heard about law of conservation of mass ?

(The energy here is insignificant with reference to mass of earth else it is law of conservation of mass+energy)

GA Sb.

milo

Law of conservation of mass is ok. But the questioner is thinking about the millions of tons of coal, crude etc sucked from the earth and burnt every year. The generated gases will go to the atmosphere, to come back in some form. Ok, the atmosphere is held by the gravity of the earth. So in total the mass remains same. But what about the weight of the earth without the atmosphere? I feel that if the burning of the earthen matters goes on, the weight of the earth will one day be less such as to be sucked by the sun due to lower gravitational power. The gravitational power of solid is probably more that that of gases. Suppose the entire atomic spaces are packed, the earth will be the size of a match box. But what happens to the power of gravity?

It is reasonable to think that some mass - that which is not sequestered in, or cycled through lithosphere, atmosphere, or oceans - is lost into the other atmosphere never to return or lost to space beyond the atmosphere...either via physical or chemical process. The question would be (?) could losses of Earth mass be said not to happen if such losses were so slight and so slow to be immeasurable(?).

Wood + oxygen →carbon dioxide + water vapour + ash.

Baby + food → adult.

It doesn't affect the mass of the earth, so long as the materials remain upon it. The materials are simply transformed from one state to another. Mass is neither created nor destroyed in chemical and biological processes.

The molecules comprising today's human population have been here a long time in various forms, and the growth in population of late has had a negligible affect on the mass of the Earth and its biosphere provided that the frame of reference includes everything upon it.

If the frame of reference doesn't include humans, then one could say that the mass of humans has gone up and the mass of the rest of the Earth has gone down slightly. Add them together and the net change is around zero.

As far as Earth's rotation and gravitational behaviour is concerned, the effect of the change has been practically zero. It doesn't spin faster or slower, or attract the Moon more strongly simply because there are twice as many humans on the planet as there were in the twentieth century, as the molecules forming them have simply been reincorporated from other places upon it.

• Changing climatic patterns have more effect on the earth's rotation than the mass of humans upon it. According to recent observations, the day length can vary by +/- 17msec depending upon which way the wind is blowing.

It's down to definition of the frame of reference again.

We burn a lot of fossile fuel that turn into gas that is lighter than solids and liquids.

No! If you burn 12 grams of Carbon with 32 grams of Oxygen, you get 44 grams of CO₂

Nothing is lost or gained. Only that 12 grams of carbon fit in a couple of tea spoons, while 44 grams of CO₂ will take quite more (one with more free time may calculate V=nRT/P to find out). Moreover, seeing the big picture, as soon as the percentage of gases in the atmosphere remains more or less the same, this means that somehow the carbon in the CO₂ created is somehow returned to the "solid" earth (and O₂ returns back to the atmosphere). How? Due to the work of the plants! The plants grow using that carbon. Animals (and humans for that matter) also grow by eating these plants. And animals that eat other animals (humans not excluded) also grow and this happens all the way up to the food chain. And people and plants grow and die in the incessant wheel of life, but in the end nothing is gained or lost, even if we talk about the "solid" earth and the atmosphere as separate entities. Of course, lately the human intervention has started to change the balance, but even in this case, the sum of the weight of earth per-se and its atmosphere is still the same, no matter what.

There is one note only that has to do with the meteorites falling on earth, or air particles that are lost to space, but I think these are infinitesimally small as compared to the overall weight of earth.

Hi Kallie. I think this is a good question. Think about burning a small pile of wood, one that would fit in a small bag. When the wood is all burned up, every atom in the wood is still here on earth. Some of it is in the ashes. The rest has gone up in smoke. The smoke is a mixture of gasses (mostly CO2 and water vapor) and soot. If you could collect all the ashes, soot and gasses, they would actually weigh MORE than the original bag of wood, because in the burning process the atoms in the wood combine with oxygen from the air. But since every atom in the wood is part of the world, and every atom of oxygen is part of the world, there has been no change in the weight of the world. There is just slightly less wood in the world now, slightly less oxygen in the earth's atmosphere, and slightly more CO2, water vapor and soot. It all evens out perfectly.

We think of gasses as weighing less than wood, because it is common sense that a bag full of air, or CO2, or water vapor, weighs just about the same as an empty bag. A bag of wood is obviously heavier. But the gasses from the fire would fill many, many bags. So the gasses are not lighter, they are just less dense.

As for all the people in the world, every single atom in your body comes from this earth. If you had lived in the old days, when we lived on farms, most of the atoms in your body would have come from your own farm, plus the little bit that came from the sugar, salt, and other foods that you would have to buy from somewhere else on earth. So in terms of how much the earth weighs, it doesn't matter how many people there are. All the atoms that make up the people came from the earth.

So as Irving says in the first answer, the weight of the earth is always pretty much the same. Small amounts of the earth's atmosphere are lost every day into space which makes the world a little bit lighter. But every day millions of tiny (and sometimes not so tiny) meteors fall to earth from space and add to the weight. The incoming meteors actually outweigh the escaping gasses, so every day the earth is actually getting heavier.

Every once in a while we use a rocket to shoot a satellite into space, and you could argue that this makes the earth a little bit lighter. But almost all of these rockets and satellites end up orbiting in space very near the earth, and almost all of them eventually fall back to earth, so any small change in weight is mostly temporary.

Given the equivalency of mass and energy, what about all the energy that impacts the earth from the sun? Wont it add up?

Earth emits back to space all the energy that it receives from the sun. That's either because a part is reflected, and another part returns as radiated heat, after giving a boost to life, meteorological phenomena and the like. If it weren't like that, then earth would continuously warm up, till the point to puff in small pieces. Of course, earth is much warmer due to the sun, than without it, but it is now some billions of years, where the system is at an equilibrium, therefore the average temperature is more or less the same, with some fluctuations that smooth out in the long run.

One might argue that it's not the radiated heat that is energy, but one should also take account of the enthalpy of various chemical reactions, and atomic transformations, that might accumulatively store solar energy. One may correct me on this, but in my opinion, the percentage of the elements and chemical substances on earth are again, more or less the same (the human actions seem to me of minor contribution to the overall business), that is all reactions happen both ways, leaving the same energy/mass sum as an average.

Well, this large object came in about 65My ago, taking out the dinosaurs and adding to the mass, and there have been others. Then, there's a continual bombardment from the Solar Wind and meteorites.

On the minus side, numerous space agencies have sent spacecraft out of the Earth/Moon system, and any free hydrogen molecules will drift away too.

So it depends upon the frame of reference, really.

With the billions of tons of micrometeorites wafting down onto the surface of the Earth, the overall mass has increased considerably since the Earth settled down to its familiar form after all major colliders stopped colliding around 3 billion years ago.

Check the statistics on say, Wikipedia and you will find that the mass of micrometeorites falling on the Earth in a year considerably outweighs the overall gain in weight of the population caused by eating McDonald products.

Micrometeorites do not burn up when entering the atmosphere because they are dust-sized and present small surface areas.

Technically, the Earth gains mass each day - as the result of falling debris from space.

No one knows for sure.

We do know that the Earth weighs more today than it did last year, and it will weigh more than it does now next year. But it may well weigh less than it did 5 billion years ago, depending on what cataclysmic events have happened since then. For instance, some say that the moon was ejected from the earth after a collision with a another large body - would that leave the earth larger or smaller?

Doesn't Earth's weight change constantly as it revolves about Sol?

The weight of earth is a very controversial subject. And it will keep on changing every second moment even if there is no matter/ energy transaction taking place .

And it is not only because of rotation of it around sun, but also because of all planets around as well as the universe.

The weight is the pull (force) due to gravity ?

On earth what is gravitational force ? it is by sun (changing due to elliptic orbit), moon, other planets ....

And If you are talking about mass - then no, due to rotation about the sun, it doesn't change.

In fact I am not sure one talks about the weight of an object of the size of the 3rd Rock or even any of the rocks/gas balloons. .

According to the experts about 250,000 tons of matter strikes the earth every day.

Ah, but there are scales to measure changes in weight of the earth...given enough time.

Simple answer, really, what goes up must come down (except for a few interplanetary probes). Everything that was on the Earth has remained here. New mass is added with each meteor that lands. Therefore, earth weighs more.

I am going to say more, since in the beginning the earth was nothing but some particles of dust, maybe slightly larger, that aggregated and the subsequent gravitational pull drew in more particles and larger particles. Even including the ejection of the moon, it must be larger that it was initially.

What Skelly says sounds about right. What's missing from this thread is the amount of mass that has been converted to energy that is lost to space in whatever wave form you choose.

kallie

If we all jumped at the same time and some one could organize a mass weighing at that time I suppose the planet could weigh a fraction less at that moment. Toyota could make an add and do the tech bit.

It would way less at that instant but would regain its mass shortly there after. In real life it would not matter because you would have to weigh the surrounding atmosphere as well. It's all part of it. Nothing can get away but alien matter does accumulate over time.

I think she has put on some weight the old Dame, Ky.

It weighs more now, people are getting fatter...

My theory was that the east coast was sinking from the weight of all the national Geograpic magazines that everyone hoards in their basements...

milo