Does the earths weight change?

Desert Eagle

I just suddenly started thinking about this. Does the earths weight change? And if so, would it be increasing or decreasing?

ummm, by weight do you mean mass or actual weight (ie gravitational force). "Weight" has little concept for the earth, since it is usually defined as the downward force towards the earth that an object has as a result of it's mass. However, if you were to define it as the equivalent, the force towards the sun, then yes it would change slightly due to the elliptical orbit. However it would be periodic.

If you meant mass, then no. It's a closed gravitationally bound system, more or less, so apart from the odd meteorite that happens to hit the earth, or anything we launch into space, it stays pretty much the same.

Reply 2

generalebriety

What does "weight" mean here? It normally means the force acting on one object due to the earth. :s-smilie:

Edit: oops, beaten. :p:

Reply 3

Desert Eagle

OP

3

ye sorry, i meant mass. Doesnt more people being born affect the mass of the earth? Or is that just a really silly thought.

Reply 4

generalebriety

Desert Eagle

ye sorry, i meant mass. Doesnt more people being born affect the mass of the earth? Or is that just a really silly thought.

Yeah, I think that's a really silly thought... it probably all leads back to food. I'm no biologist, but I know babies don't just grow from nothing. :wink:

Reply 5

Desert Eagle

OP

3

lol ok, cheers for the response. This place is great, i can ask stupid questions and not feel embarrassed after :biggrin:

Reply 6

Drummy

at the risk of talking a load of cobblers...

i reckon we might be losing a bit of atmosphere. Some of it (the odd molecule) may have enough energy to escape the earth's field and maybe some of it gets blasted away by the solar wind, just like a comet.

what do you think?

Reply 7

pikaboo

13

I read in a crazy facts book that the Earth is getting heavier because it's collecting more and more dust :smile:

Reply 8

generalebriety

pikaboo

I read in a crazy facts book that the Earth is getting heavier because it's collecting more and more dust :smile:

...

...space dust? :s-smilie:

Reply 9

Desert Eagle

OP

3

house dust more like.... come to think of it, how is dust created? lol

Reply 10

Dirac Delta Function

14

Desert Eagle

house dust more like.... come to think of it, how is dust created? lol

much of it is dead skin.

original question: I would have thought the Earth would be losing mass, albeit slowly, due to evaporation.

Reply 11

Dirac Delta Function

much of it is dead skin.

original question: I would have thought the Earth would be losing mass, albeit slowly, due to evaporation.

Well, it all depends on what you are defining to be the "Earth". Normally, given the dynamic relationship between land, ocean and atmosphere, one would class the atmosphere as part of the Earth. If this is the case, then the atmosphere being gravitationally bound, would still retain matter within it. If it was not gravitationally bound we probably wouldn't have much of an atmosphere left by now, although there may be some continued escape of very light gases.

As for the issue of more people - they don't appear from nowhere. They are created from the molecules already present on Earth. They do not spontaneously appear. However, I consider these people to contribute to the mass of the Earth too. On the scale of the Earth's mass they are insignificant anyway.

Reply 12

Drummy

except for americains?

Reply 13

bikerx23

1

The earth will potentially lose mass from loss of the atmosphere to space - this is accelerated at times of magnetic field instability, as as mentioned, part of it is torn from the earth by the solar wind (an example of this can be seen on mars, whose atmosphere has been almost completely purged following its loss of magnetic field due to a small core and rapid cooling).

Also - as has been mentioned - people eat stuff - don't all be so ridiculously vacuous!

Reply 14

bikerx23

Also - as has been mentioned - people eat stuff - don't all be so ridiculously vacuous!

what goes in must come out... :p:

Reply 15

bikerx23

1

F1 fanatic

what goes in must come out... :p:

In the form of ridiculous comments?

Reply 16

Drummy

If you believe that the destiny of mankind is to escape the earth and populate other systems in the galaxy, like what happened on battlestar galactica, then I calculate a 0.023% reduction in the mass of the Earth. So there.

Reply 17

Drummy

If you believe that the destiny of mankind is to escape the earth and populate other systems in the galaxy, like what happened on battlestar galactica, then I calculate a 0.023% reduction in the mass of the Earth. So there.

like I said... insignificant. :p:

Reply 18

bikerx23

1

Drummy

If you believe that the destiny of mankind is to escape the earth and populate other systems in the galaxy, like what happened on battlestar galactica, then I calculate a 0.023% reduction in the mass of the Earth. So there.

You do realise you're in a science forum, yea? Those concepts are what would be perceived as eventually inevitable (well, withink 5 billion years), but it would be ridiculously unlikely for humans to hang around long enough for it to be an issue!

Reply 19

Davetherave