# Does earth mass get heavier?

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Janus
Staff Emeritus
Gold Member
Why isn't it simply what @DaveC426913 suggested?

I think the EMR part sums up to zero for it's either used by lifeforms or radiated back in space
Not quite all of it. Sometimes vegetation converts solar energy to chemical energy which is not released but remains stored. This is where our oil reserves came from; The energy we get from them is, in effect, stored solar energy. ( Of course, now that we are pulling it out of the Earth and burning it, we are releasing this energy back into the environment.)

fresh_42
Mentor
Yes. ##S(t)## is probably the most difficult part of the equation. The oil example shows, that ##S(t)## (sun) isn't simply a linear function, but varies on large timescales. Unfortunately I can't remember a source, but I think that I've recently heard, that the ##A(t)## term above, i.e. the loss on atmosphere is by far the biggest cost factor - something about millions of tons a year. Since ##J## (meteors / space junk) and ##R## (rockets) are easy to compute, resp. estimate, it all comes down to the atmospheric question and the actual form of ##S(t)##. In the end, the sun is the only input that keeps the system earth from being closed.

As I've already read figures here for ##J## and ##R##, does anyone know, which amount of atmosphere we (on average) annually lose?

davenn
Gold Member
We are aware that we defecating everyday. It should add up. Animals,too.

where do you think all that excretion came from for a start ??

Bystander
Homework Helper
Gold Member
"Does earth mass get heavier?"
"Heavier" implies "weight," or force. Should we examine the implication? Given that the sun is losing mass at 1.5 million tons per second, the earth should be losing "weight."

Cutter Ketch,

Yesterday you brought up an interesting point. Mass convert to Energy. But this morning I ask myself " if it's true, why not the earth convert to energy as well?

jbriggs444
Homework Helper
Cutter Ketch,

Yesterday you brought up an interesting point. Mass convert to Energy. But this morning I ask myself " if it's true, why not the earth convert to energy as well?
As others have said, mass-energy equivalence is a drop in the bucket -- irrelevant for this purpose.

What do you mean by "earth convert to energy"?

mfb
Mentor
Mass cannot suddenly disappear. Chemical and nuclear reactions release a tiny fraction of the mass of the involved atoms as energy. Most of the possible reactions happened in the past already.

davenn
Gold Member
"Does earth mass get heavier?"
"Heavier" implies "weight," or force. Should we examine the implication? Given that the sun is losing mass at 1.5 million tons per second, the earth should be losing "weight."
what is your reasoning there ??

Bystander
Homework Helper
Gold Member
what is your reasoning there ??
Less attractive force between the earth and the sun.

DaveC426913
Gold Member
Less attractive force between the earth and the sun.
Ah. I see what he did there.

The Earth's weight is determined by the Sun's gravity. Sun's mass is shrinking, so Earth's weight is shrinking

Janus
Staff Emeritus
Gold Member
Ah. I see what he did there.

The Earth's weight is determined by the Sun's gravity. Sun's mass is shrinking, so Earth's weight is shrinking
But since the Earth is following a free-fall trajectory, it is technically weightless.

davenn
Bystander
Homework Helper
Gold Member
a free-fall trajectory,
An expanding/growing free-fall trajectory; i.e., the force exerted by the sun is decreasing, so, technically less than weightless.

Cutter Ketch
An expanding/growing free-fall trajectory; i.e., the force exerted by the sun is decreasing, so, technically less than weightless.
Oohhh!!! I like that. It's drifting up. It must be less than weightless! Ok, I don't think that's going in the textbooks anytime soon, but it's funny.

davenn
Gold Member
Less attractive force between the earth and the sun.
The Earth's weight is determined by the Sun's gravity. Sun's mass is shrinking, so Earth's weight is shrinking
That mite affect the weight of the earth but it doesn't affect the mass of the earth

and since the OP is talking about the MASS of the Earth ... it's weight in any gravity field is irrelevant
particularly in an orbit

hence Janus's response
But since the Earth is following a free-fall trajectory, it is technically weightless.

As per my knowledge, having more people or trees doesn't add any mass to the planet. Humans and things are done with the matter that is already on the planet. It's just been transformed.