Why is the Earth electrically neutral?

[Bluemoon]

The Wikipedia article for Cosmic ray { http://en.wikipedia.org/wiki/Cosmic_ray} says that they are mostly positively charged and

that electrons (beta particles) constitute about 1% of galactic cosmic rays.

 

The ones that impact on the earth's rocky surface must remain trapped inside it forever.

However, the Earth appears to have no net charge, so what is the source of the electrons that offset this embedded Cosmic ray charge and how do they arrive?

 

Also, is it likely to be so that whatever the sources are of Cosmic rays, that they must, after 13 billion years, now have an enormous -ve charge;

or that the positive partners to Earth's neutralizing electrons drift across space to neutralize that source (presumably after radiativley spiraling in).

[elfmotat]

Any imbalance will tend to cancel out over time. Think about it: if some large positive charge builds up on Earth, then what happens? Positively charged cosmic rays will be repelled very strongly, and negatively charged rays will be attracted very strongly. So Earth will start accumulating more negative charges until the planet is electrically neutral again.

[Enthalpy]

Many charges flow to and from Earth, over which cosmic rays are a tiny part. For instance, an energetic particle arriving in Earth's atmopshere will create many particle pairs there, of which some must be capable to leave Earth. And you have the solar wind, whch I'd say is the biggest contributor - if it's not the ionization of the upper atmosphere by Sun's UV light.

 

Earth is approximately neutral because an excessive imbalance would result in a stronger electric field that would help the excess charges leave and retain the minority charges stronger.

 

A strong voltage at Earth would already be noticed, since it would change the mean energy of the electrons that arrive.

 

Since Earth's capacitance is small, a limited voltage means a small net electric charge, for sure tiny as compared with the number of electrons and protons that constitute the Earth. R=6370km make only 700µF, so 100kV imbalance (for no reason, but >1022kV would be noticed) make only 71C or 4e20 electrons. Earth weighs 6e24 kg so it contains 4e51 protons and neutrons, over 1e51 electrons. Pretty much neutral.

[Robittybob1]

The Wikipedia article for Cosmic ray { http://en.wikipedia.org/wiki/Cosmic_ray} says that they are mostly positively charged and

that electrons (beta particles) constitute about 1% of galactic cosmic rays.

 

The ones that impact on the earth's rocky surface must remain trapped inside it forever.

However, the Earth appears to have no net charge, so what is the source of the electrons that offset this embedded Cosmic ray charge and how do they arrive?

 

Also, is it likely to be so that whatever the sources are of Cosmic rays, that they must, after 13 billion years, now have an enormous -ve charge;

or that the positive partners to Earth's neutralizing electrons drift across space to neutralize that source (presumably after radiativley spiraling in).

I have been looking for some sort effect like this for a few months now. Could there even be fluctuations in the electrical balance in the Earth which reflects the charge in the Outer Core causing magnetic pole reversal? If for long periods there is net positive and then changing to net negative charge, the flow of the charged stream of molten metal would represent an alternating current, would it not?

[Sensei]

Significant quantity of similar charges is easily visible:

 

 

Not charged (neutral):

 

 

Do you see on the streets people walking with hairs pointing each one in different direction (other than punks)?

 

[Fuzzwood]

Also: http://en.wikipedia.org/wiki/Van_Allen_radiation_belt

[Bluemoon]

elfmotat >" So Earth will start accumulating more negative charges ... "

From where though?

RE: OP:- " ... so what is the source of the electrons that offset this embedded Cosmic ray charge and how do they arrive? "

 

Sensei

What part of the OP:- " However, the Earth appears to have no net charge ...." is an invitation to post your Selfie ?

 

Fuzzwood >" Also: http://en.wikipedia...._radiation_belt "

... and .... ? !

 

Enthalpy > ".. the solar wind, whch I'd say is the biggest contributor - if it's not the ionization of the upper atmosphere ..."

Do they diffuse down or occasionaly discharge down as lightning?

 

What of the Cosmic Ray sources? The surface flux on Earth is ~1000/sqm/s.

I make that a charge of 80mC/s impacting over the Earth's surface ---> ~2.5MC/year and that's just the Earth!

Over the Solar system or maybe the galaxy then something somewhere is surely getting Very negatively charged?

[Bluemoon]

I now don't think that my question was aswerable.

It looks like the whole issue of the Earth's charge is very much more complex than I ever imagined:-

en.wikipedia.org/wiki/Atmospheric_electricity

[Robittybob1]

I now don't think that my question was aswerable.

It looks like the whole issue of the Earth's charge is very much more complex than I ever imagined:-

en.wikipedia.org/wiki/Atmospheric_electricity

I would like to see you carry on though. Find out if the Earth's charge could change. (Notice how the net charge may be over all neutral but it can be layered.)

Edited November 29, 2014 by Robittybob1

[Softdude]

Maybe the question is better put: Dies the Earth have a surplus of electrons, a deficiency, or is it in balance? Does the solar wind buffeting the magnetosphere deposit electrons, strip electrons, or perhaps neither. Does our everyday chemistry depend on the absolute quality of available electrons? How would you even know the answer if you don’t know the mechanisms that are in play.  Too few electrons might cause the field to collapse, equalizing or increasing the number of electrons, starting the cycle anew. 

[swansont]

On 8/10/2019 at 11:00 PM, Softdude said:

Maybe the question is better put: Dies the Earth have a surplus of electrons, a deficiency, or is it in balance? Does the solar wind buffeting the magnetosphere deposit electrons, strip electrons, or perhaps neither. Does our everyday chemistry depend on the absolute quality of available electrons? How would you even know the answer if you don’t know the mechanisms that are in play.  Too few electrons might cause the field to collapse, equalizing or increasing the number of electrons, starting the cycle anew. 

I think you could put limits on whatever the possible discrepancy might be between + and - charges. At some point charge isn't going to build up anymore, owing to Coulomb repulsion, which is a lot stronger than gravitational attraction

There is no dearth of electrons for everyday chemistry. The mass of the earth is 6 x 10^24 kg, and that's roughly 3 x 10^26 of each per kg of matter (assuming protons and neutrons are about equal in number). So around 10^51 of each.

 

 

———

edit to add:

Assuming my math is right (feel free to check), if we equate the coulomb repulsion and gravitational attraction for an electron, for any r outside of the earth (assuming the charge is equally distributed), then it requires just 250 nanoCoulombs of charge — spread out over the surface — to make the forces equal. That puts a limit on how much excess electron charge could accumulate from the outside

[John Cuthber]

I was wondering if you could get the same result by calculating the voltage needed to accelerate an electron ( or proton) to the escape velocity.

Then use the capacitance of the earth (modeled as a conducting isolated sphere) to calculate the charge.

However, I'm tired so I'm off to bed.