Electrostatic potential between the Sun and the Earth

What is the electrostatic potential between the sun and the earth?

Also how does the electrostatic force between the sun and the earth compare
to the gravitational force between the sun and the earth?

"Duncan Macdonald" wrote in message ...
What is the electrostatic potential between the sun and the earth?

Also how does the electrostatic force between the sun and the earth compare
to the gravitational force between the sun and the earth?

Should be very low, practical zero. What creates electrostatic
potential is electrical charge, which results from the proton/electron
imbalance. Neither the Sun nor the Earth have any significant charge
in the body as a whole. The Sun, being hotter, does lose some
electrons, but the effect is ultimately insignificant.

Electrical force at the particle level is much stronger than gravity,
and can even overpower nuclear forces. However, gravitational force
adds up much more efficiently at the larger scale, thus being the
dominating force for all cosmic objects.

Vlad

Why would the potential of the sun be near zero ?

Assuming that the sun started off with no net charge, the following
conditions should soon (in astronomical terms) leave the sun with a high
positive charge.

1) Electrons weigh a lot less than protons
2) It therefore takes far less energy to accelerate an electron to escape
velocity than it does to accelerate a proton to escape velocity
3) The initial solar wind should therefore have more electrons than protons
in it until the positive charge built up on the sun to the point that it
exerted sufficient extra attractive force on the electrons and repulsive
force on the protons to cause the solar wind to be neutral.

I do not know what this potential would be but I doubt that it is anything
near zero.

"Duncan Macdonald" wrote in message
...
Why would the potential of the sun be near zero ?

Assuming that the sun started off with no net charge, the following
conditions should soon (in astronomical terms) leave the sun with a high
positive charge.

1) Electrons weigh a lot less than protons
2) It therefore takes far less energy to accelerate an electron to escape
velocity than it does to accelerate a proton to escape velocity
3) The initial solar wind should therefore have more electrons than protons
in it until the positive charge built up on the sun to the point that it
exerted sufficient extra attractive force on the electrons and repulsive
force on the protons to cause the solar wind to be neutral.

I do not know what this potential would be but I doubt that it is anything
near zero.

Any net charge would attract its opposite and there would
quickly arise a cancellation. Net electric charge is not
very long-lived in the universe.

Note that a large component of the solar wind is protons.
Eventually these would "sop up" any lone electrons and form
hydrogen.

For the current net solar wind to be electrically neutral, there has to be
something compensating for the fact that electrons can be accelerated to
solar escape velocity more easily than protons.

The only mechanism that I can see that could do the compensation is for the
sun to have a net positive charge.


This is a dynamically generated and maintained charge - if the potential
falls then more electrons escape and the potential increases, if the
potential rises then fewer electrons escape and the potential decreases.

When (in several billion years) the sun has finally cooled down to a black
dwarf, there will be no solar wind and the charge will finally drop to zero
as there will be nothing to maintain the charge but at the moment the solar
energy generation provides the power source to maintain the charge.

Midjis wrote
I do recall - I think - reading something at
one point about electrical 'interference' (if that is the right word)
between Io and Jupiter. Does this occur? If so I assume it would be due
to electrical activity in Jupiter's high atmosphere and the intensely
volcanic nature of Io (which I assume is itself a consequence of the moon's
proximity to such a large gravity source)

You may be thinking of the flux tube between Io and Jupiter (detected by
Voyager). Try this link
http://www.solarviews.com/eng/vgrjup.htm
and scroll down to Magnetosphere

Denis
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DT
Replace nospam with the antithesis of hills

In message , Duncan
Macdonald writes
For the current net solar wind to be electrically neutral, there has to be
something compensating for the fact that electrons can be accelerated to
solar escape velocity more easily than protons.

The only mechanism that I can see that could do the compensation is for the
sun to have a net positive charge.


This is a dynamically generated and maintained charge - if the potential
falls then more electrons escape and the potential increases, if the
potential rises then fewer electrons escape and the potential decreases.

When (in several billion years) the sun has finally cooled down to a black
dwarf, there will be no solar wind and the charge will finally drop to zero
as there will be nothing to maintain the charge but at the moment the solar
energy generation provides the power source to maintain the charge.



There seems to be a large literature on electron velocity in the solar
wind, most of which is way over my head!
But I suspect that your comment that electrons "can" be accelerated to
higher speed is irrelevant. As soon as any such charge separation
occurred electrostatic effects would come into play, and they are much
larger than gravity.
I did notice that John Gard's site at
http://www.1stardrive.com/solar/wind.htm seems to support your view.
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Remove spam and invalid from address to reply.

"Duncan Macdonald" wrote in message . ..

Assuming that the sun started off with no net charge, the following
conditions should soon (in astronomical terms) leave the sun with a high
positive charge.

1) Electrons weigh a lot less than protons
2) It therefore takes far less energy to accelerate an electron to escape
velocity than it does to accelerate a proton to escape velocity
3) The initial solar wind should therefore have more electrons than protons
in it until the positive charge built up on the sun to the point that it
exerted sufficient extra attractive force on the electrons and repulsive
force on the protons to cause the solar wind to be neutral.

I do not know what this potential would be but I doubt that it is anything
near zero.

The process is pretty much as you have outlined. Still, calculation
based on
the positive potential energy of a proton being equal to the negative
gravitational energy gives the maximim possible electrical potential
of ~2000 volts. Actual value of the solar potential is significantly
smaller, taking into account its radiation-pressure (thermal) forces
(and some other factors).
It is very low; "practical zero" was meant to characterize its force
relative to that of the gravity, as stated in the initial question.

Vlad

"DM" == Duncan Macdonald writes:

DM What is the electrostatic potential between the sun and the earth?
DM Also how does the electrostatic force between the sun and the
DM earth compare to the gravitational force between the sun and the
DM earth?

Let's turn the question around. How much charge would have to be on
the Earth and Sun for their electrostatic attraction (or repulsion) to
equal their gravitational attraction?

Because both forces are 1/r^2 forces, our problem simplifies to

G*M_E*M_S = Q_E*Q_S/(4*pi*eps_0).

Let's assume that the ratio of the charges is the same as the ratio of
the masses, M_E/M_S = Q_E/Q_S = 3E-6. Knowing a few other constants,
G = 6.67E-11 N m^2/kg^2 and eps_0 = 8.8542E-12 farad/m, we find that
Q_E*Q_S = 8.9E34, or with our simplifying assumption,

Q_S = 5.2E20 C.

The charge on an electron is 1.6E-19 C, so this charge is equivalent
to 3.2E39 electrons on the Sun.

That sounds like a big number, but remember that the mass of the Sun
is M_S = 2E30 kg and the mass of a hydrogen atom is about 1.67E-27 kg,
or that there are about 1.2E57 hydrogen atoms or electrons in the Sun.
We conclude that if the charge on the Sun deviated from neutral by
more than about one part in 1E17, the electrostatic forces would begin
to overwhelm the gravitational forces.

In other words, the Sun is neutral to a very good approximation.

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Interesting!
Changing the subject a bit ...
The Earth is (I'm assuming) very nuetral electrostatically so even if the
Sun had a strong electrostatic field about it, there would be no effect ...

We know that there is a steady stream of charged particles (mostly electrons
(I assume)) leaving the Sun (The Solar Wind) ... what is the electrostatic
strength of this field I wonder? Suppose two white dwarf stars were orbiting
one another ... would the electrostatic forces between them be significant
(assuming White Dwarfs have Solar Winds too)?
Al


"Joseph Lazio" wrote in message
...
"DM" == Duncan Macdonald writes:

DM What is the electrostatic potential between the sun and the earth?
DM Also how does the electrostatic force between the sun and the
DM earth compare to the gravitational force between the sun and the
DM earth?

Let's turn the question around. How much charge would have to be on
the Earth and Sun for their electrostatic attraction (or repulsion) to
equal their gravitational attraction?

Because both forces are 1/r^2 forces, our problem simplifies to

G*M_E*M_S = Q_E*Q_S/(4*pi*eps_0).

Let's assume that the ratio of the charges is the same as the ratio of
the masses, M_E/M_S = Q_E/Q_S = 3E-6. Knowing a few other constants,
G = 6.67E-11 N m^2/kg^2 and eps_0 = 8.8542E-12 farad/m, we find that
Q_E*Q_S = 8.9E34, or with our simplifying assumption,

Q_S = 5.2E20 C.

The charge on an electron is 1.6E-19 C, so this charge is equivalent
to 3.2E39 electrons on the Sun.

That sounds like a big number, but remember that the mass of the Sun
is M_S = 2E30 kg and the mass of a hydrogen atom is about 1.67E-27 kg,
or that there are about 1.2E57 hydrogen atoms or electrons in the Sun.
We conclude that if the charge on the Sun deviated from neutral by
more than about one part in 1E17, the electrostatic forces would begin
to overwhelm the gravitational forces.

In other words, the Sun is neutral to a very good approximation.

--
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