Poll about the Earth's mass

[Brom]

A friend and I were having a discussion about whether the Earth is gaining or losing mass over time.

Some factors the lead to it losing mass are: launching satellites and other objects into space, and ejection from impact sites/volcanoes/nukes possibly. The main factor leading to the Earth gaining mass is: meteorites and space dust/debris landing on Earth.

Which of these factors do you think is greater? Also, only vote they are exactly the same if you honestly feel that no one factor is great at all. If you think one is even minutely greater, then vote for it.

Also any comments, links, ideas, etc. you might want to voice.

[vhawk01]

Well, there are LOTS of other ways that the eart can be gaining or losing mass. First off, solar energy is ultimately absorbed and converted into skyscrapers, cities, humans, animals and everything else. I still dont know if that necessarily leads into an increase or a decrease, but its more food for thought.

[MidGe]

As vhawk01 said, there are many other ways the earth loose/gain mass. One thing I am certain about is that the rockets/satellites weight/mass is probably insignificant in the calculation. It is much too small to worry about in comparison to the other exchanges.

[TomBrooks]

How about the population explosion. How much mass is being added by the increased number of people? Or do people grow by assimilating existing earth minerals like carbon. Only about 10% of the mass of people would count at most as 90% of a person is water and that comes from existing sources.

[Copernicus]

[ QUOTE ]
How about the population explosion. How much mass is being added by the increased number of people? Or do people grow by assimilating existing earth minerals like carbon. Only about 10% of the mass of people would count at most as 90% of a person is water and that comes from existing sources.

[/ QUOTE ]

No mass is added by population growth, just as no mass is added by pulling together disparate parts and assembling a car.

Which leads to another question...if god created Adam and Eve, did he create them by "assembly" or by "spontaneous appearance" (correct that term if there is an existing one!)

Same question for all the animals, and anything else he created.

If they were not by assembly, but "poof" they appeared, did they appear in significant enough quantities to alter the mass of the earth, and therefore change gravitational effects such as distance from the sun, orbit, etc?

Was there any particular "day" of creation where most of the mass would have been added? If "Day" is metaphorical for a longer period of time, and there was significant mass added in one of those periods, is there geological evidence of gravitational shifts? Eg floods? increase in temperature? that correspond to that period?

[Sharkey]

My guess is that all those meteors hitting the atmosphere add up to more than whatever might be escaping.

As far as energy from the sun goes, I think that averages to about 200 watts per square meter. If that’s correct, the mass equivalent is trivial.

[surftheiop]

Im pretty sure in "a short history of nearly everything" it said that a few tons of microscopic space dust fall to the earth each year but its so spread out it isnt noticed accumulating or anything like that.

[Matt R.]

I would think that the mass has to be increasing simply due to gravity. The Earth would "collect" anything that is passing by at a small enough distance and velocity. Relative to all the tiny pieces of matter that presumably are caught in the Earth's gravitational field, I would think anything that we send into space is trivially small in mass. And I don't think there are too many earthbound objects that can "naturally" reach escape velocity.

[morphball]

When a satellite is launch, has earth's mass changed? The satellite is still part of earth's rotational inertia etc., etc.

How much of earth's atmosphere is lost due to solar winds pushing off molecules from the upper atmosphere everyday?

[guesswest]

I have no idea what the answer to this question is - but I'm sure you won't be the first person to have asked it, it seems like it'd be pretty important for a bunch of reasons. I'm willing to bet there's some study/research out there that provides a pretty good answer - I dunno what to google exactly though.

[evil twin]

[ QUOTE ]
Well, there are LOTS of other ways that the eart can be gaining or losing mass. First off, solar energy is ultimately absorbed and converted into skyscrapers, cities, humans, animals and everything else.

[/ QUOTE ]
No.

[Guyon]

Earth is the dominant gravitational force in the neighborhood. Anything in the area is coming in, but not much, if any is going out.

[Silent A]

[ QUOTE ]
Earth is the dominant gravitational force in the neighborhood. Anything in the area is coming in, but not much, if any is going out.

[/ QUOTE ]
Radiation gets out, but that's almost exactly balanced by solar radiation coming in.

[purnell]

[ QUOTE ]
Well, there are LOTS of other ways that the eart can be gaining or losing mass. First off, solar energy is ultimately absorbed and converted into skyscrapers, cities, humans, animals and everything else. I still dont know if that necessarily leads into an increase or a decrease, but its more food for thought.

[/ QUOTE ]

You are talking about photosynthesis, right? No mass is added to the Earth by respiring plants. They absorb carbon from the air, hydrogen from water, and a few other elements from the soil in small amounts, and reassemble these elements into, well, themselves. No matter is created in this process.

[vhawk01]

Yeah, it wasnt the best example. There is a LOT of energy that is absorbed, but the mass of that is probably fairly small, as someone already mentioned. Its converted into work, and decreased entropy, but probably not much of it adds mass.

[FlFishOn]

"Radiation gets out, but that's almost exactly balanced by solar radiation coming in."

If this is true then the Earth is gaining mass. I was thinking of the internal nuclear fission and the lost mass but if the net energy balance is even then space debris accretion tips the scale.

[Siegmund]

A lot more mass is coming in than going out.

In order to escape the earth's gravitational pull and continue out into space indefinitely, an object has to either have an ongoing source of propulsion, or achieve a speed of about 10 km/sec as it leaves the atmosphere.

Hydrogen molecules in the upper atmosphere bounce around at an average speed around 2 km/sec, and on rare occasion achieve escape velocity by chance: it is no coincidence that our atmosphere contains almost no hydrogen, while heavier Jupiter contains quite a lot.

Anything much heavier than a hydrogen molecule, however -- for instance, molecules of water vapor or oxygen, have essentially no chance of escaping into space. Likewise for other heavier sustances like the 'smoke' from a burnt-up meteor entering the atmosphere, doomed to stay here forever (barring the temperature increasing thousands of degrees, anyway.)

The hydrogen all being locked up in larger molecules, nowhere for total mass to go but to rise. The incoming mass flux has been estimated at anywhere from a few hundred to several thousand tons a day.

If you'd like to compare the amount of solar energy absorbed vs. radiated, and do the E=mc^2 thing, you may... but it will be a very small mass equivalent.

[benjdm]

[ QUOTE ]
How about the population explosion. How much mass is being added by the increased number of people?

[/ QUOTE ]

YSSCKY

[Silent A]

[ QUOTE ]
If you'd like to compare the amount of solar energy absorbed vs. radiated, and do the E=mc^2 thing, you may... but it will be a very small mass equivalent.

[/ QUOTE ]
There's no point because the difference between solar radiation in and thermal radiation out has to be very close to zero. If it wasn't then global warming/cooling would be very, very fast indeed. We'd either completely melt the ice caps or find the earth in a massive almost irreversible ice age.

[Duke]

[ QUOTE ]
How about the population explosion. How much mass is being added by the increased number of people? Or do people grow by assimilating existing earth minerals like carbon. Only about 10% of the mass of people would count at most as 90% of a person is water and that comes from existing sources.

[/ QUOTE ]

This is an excellent point. The angels that come down to sprinkle dust on growing children add to the mass with said dust.

~D

[ChromePony]

Im fairly sure I remember learning that the Earth is indeed gaining mass, if just from the various cosmic dust and whatnot that settles down here. If you think about it it makes sense because of the whole gravitational attraction thing, I also remember that it sure isnt very much...pretty insignificant I believe.

[ChromePony]

[ QUOTE ]
When a satellite is launch, has earth's mass changed? The satellite is still part of earth's rotational inertia etc., etc.

How much of earth's atmosphere is lost due to solar winds pushing off molecules from the upper atmosphere everyday?

[/ QUOTE ]

Is the moon still part of the Earth's mass?

It is kind of interesting to think about where the Earth ends though from a mass standpoint, is it 10 miles up, inside the atmosphere, or attached to the ground. I think its really just a semantic argument, unless theres some official guideline somewhere (probably).

[HotPants]

[ QUOTE ]
I think its really just a semantic argument

[/ QUOTE ]

I'd say that

I went to this like talk-thing where some guys were debating whether or not our solar system had a 10th planet. I quickly realized I didn't care, and I wanted to shoot myself while listening to the debate.

[PokerPadawan]

I think the primary incoming material is interplanetary dust and small bodies, such as comets and meteors. The primary outgoing material is hydrogen gas and protons and electrons from the hot, outer parts of the atmosphere, where the temperature is high enough that a small fraction of particles are moving fast enough to gravitationally escape.

Fortunately for us, the Earth's magnetic field greatly reduces, in various ways, the loss of atmosphere. So I answered that the Earth is gaining mass, since I suspect that interplanetary dust particles (IDPs) and small bodies win over atmospheric escape.

Photons probably have zero mass, so they don't contribute. Not sure why everyone is talking about radiation.