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Planet's density



 
 
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  #1  
Old December 9th 12, 06:58 PM posted to uk.sci.astronomy
Szczepan Bialek
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Posts: 51
Default Planet's density

The density of the Earth is 5.52

The Mars has 3.95 and The Moon 3.34

Is the density the diameter dependent?
S*


  #2  
Old December 10th 12, 05:10 PM posted to uk.sci.astronomy
Barry Schwarz[_2_]
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Posts: 52
Default Planet's density

On Sun, 9 Dec 2012 18:58:54 +0100, "Szczepan Bialek"
wrote:

The density of the Earth is 5.52

The Mars has 3.95 and The Moon 3.34

Is the density the diameter dependent?
S*

Density is simply mass divided by volume. The volume of a sphere is
directly related to the cube of the diameter. So in some sense, the
density is affected by the diameter.

For two objects with the same diameter, the one with more mass has the
greater density. Similarly, for two objects with the same mass, the
one with the smaller diameter has the greater density.

In the real world, the overall density of an object is determined by
the density of the matter it is made up of, almost like a weighted
average. Hence, neutron stars with small diameters have very high
densities while asteroids of similar dimensions have more typical
densities.

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  #3  
Old December 10th 12, 08:17 PM posted to uk.sci.astronomy
Szczepan Bialek
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Posts: 51
Default Planet's density


"Barry Schwarz" napisal w wiadomosci
...
On Sun, 9 Dec 2012 18:58:54 +0100, "Szczepan Bialek"
wrote:

The density of the Earth is 5.52

The Mars has 3.95 and The Moon 3.34

Is the density the diameter dependent?
S*

Density is simply mass divided by volume. The volume of a sphere is
directly related to the cube of the diameter. So in some sense, the
density is affected by the diameter.

For two objects with the same diameter, the one with more mass has the
greater density. Similarly, for two objects with the same mass, the
one with the smaller diameter has the greater density.

In the real world, the overall density of an object is determined by
the density of the matter it is made up of,


The Earth, Moon and Mars are simmilar and are close to each other.

The differences are rather big. So should be a lot of theories to explain
this phenomenon.
Are such theories?
S*



  #4  
Old December 10th 12, 10:34 PM posted to uk.sci.astronomy
Richard Tobin
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Posts: 230
Default Planet's density

In article ,
Szczepan Bialek wrote:

The density of the Earth is 5.52

The Mars has 3.95 and The Moon 3.34


The density of the moon is very similar to that of the earth's mantle,
which is one piece of evidence for the moon having been formed in a
collision between the earth and some other body. The earth retained
its dense metal core and the moon was formed from part of the lighter
outer material.

Mars's density may be due to its having a smaller core than the earth.

-- Richard
  #5  
Old December 11th 12, 12:36 AM posted to uk.sci.astronomy
Dave Liquorice[_2_]
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Posts: 29
Default Planet's density

On Mon, 10 Dec 2012 20:17:20 +0100, Szczepan Bialek wrote:

The density of the Earth is 5.52

The Mars has 3.95 and The Moon 3.34

Is the density the diameter dependent?


No, density is mass per unit volume.

The Earth, Moon and Mars are simmilar and are close to each other.

The differences are rather big. So should be a lot of theories to
explain this phenomenon. Are such theories?


Donno what exists out there but the obvious one goes back to the
formation of these objects. The smaller ones have a lower gravitational
field so stuff being attracted won't hit as hard as stuff attracted toa
larger object. The objects themselves will also have less tendancy to
collaspe onto themselves. Thus the smaller objects will tend to be less
dense.

--
Cheers
Dave.



  #6  
Old December 11th 12, 09:53 AM posted to uk.sci.astronomy
Szczepan Bialek
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Posts: 51
Default Planet's density


"Richard Tobin" napisa³ w wiadomo¶ci
...
In article ,
Szczepan Bialek wrote:

The density of the Earth is 5.52

The Mars has 3.95 and The Moon 3.34


The density of the moon is very similar to that of the earth's mantle,
which is one piece of evidence for the moon having been formed in a
collision between the earth and some other body. The earth retained
its dense metal core and the moon was formed from part of the lighter
outer material.

Mars's density may be due to its having a smaller core than the earth.


We know the GM only. The G (gravitational constant) was mesured by Cavendish
on the Earth surface where is the excess of electrons.
On the Moon is the electrostatic levitation of the dust.
So the G may be incorrect. It is possible that the planets do not have metal
cores.

It would be interested to know the measurements done on the ISS. ISS is a
"planet" which mass is known and not small.
Does ISS attract the cosmonauts or repel them?
S*


  #7  
Old December 12th 12, 02:16 AM posted to uk.sci.astronomy
Barry Schwarz[_2_]
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Posts: 52
Default Planet's density

On Tue, 11 Dec 2012 09:53:39 +0100, "Szczepan Bialek"
wrote:

We know the GM only. The G (gravitational constant) was mesured by Cavendish
on the Earth surface where is the excess of electrons.


For some reason you think the electrons have some effect on the
measurement of G. Since the Earth has more water than the moon or
Mars, maybe that affects the measurement of G also.

On the Moon is the electrostatic levitation of the dust.
So the G may be incorrect. It is possible that the planets do not have metal
cores.


The supposition is the gas giants don't.

It would be interested to know the measurements done on the ISS. ISS is a
"planet" which mass is known and not small.


Compared to almost any other non-manmade object, the mass of the ISS
is quite small.

Does ISS attract the cosmonauts or repel them?


And it would repel them because? The gravitational force between two
objects is proportional to the product of their masses. There is no
**noticeable** attraction between the ISS and the supply ships that
dock with it periodically. The mass of the supply ship is orders of
magnitude more than the mass of a cosmonaut. The attraction between
the ISS and a cosmonaut would therefore be orders of magnitude less.

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  #8  
Old December 12th 12, 10:04 AM posted to uk.sci.astronomy
Szczepan Bialek
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Posts: 51
Default Planet's density


"Barry Schwarz" napisal w wiadomosci
...
On Tue, 11 Dec 2012 09:53:39 +0100, "Szczepan Bialek"
wrote:

We know the GM only. The G (gravitational constant) was mesured by
Cavendish
on the Earth surface where is the excess of electrons.


For some reason you think the electrons have some effect on the
measurement of G. Since the Earth has more water than the moon or
Mars, maybe that affects the measurement of G also.

On the Moon is the electrostatic levitation of the dust.
So the G may be incorrect. It is possible that the planets do not have
metal
cores.


The supposition is the gas giants don't.


If "the electrons has some effect on the measurements of G" than the
terrestial planets also do not.
The only "cause" of the metal core is the calculated density 5.5.

It would be interested to know the measurements done on the ISS. ISS is a
"planet" which mass is known and not small.


Compared to almost any other non-manmade object, the mass of the ISS
is quite small.


But bigger than the Cavendish masses.

Does ISS attract the cosmonauts or repel them?


And it would repel them because?


Everything in the space have the excess of electrons. In such case the small
objects repel. Like the dust and fog (water droplets) in the air.

The gravitational force between two
objects is proportional to the product of their masses. There is no
**noticeable** attraction between the ISS and the supply ships that
dock with it periodically. The mass of the supply ship is orders of
magnitude more than the mass of a cosmonaut. The attraction between
the ISS and a cosmonaut would therefore be orders of magnitude less.


And the repulsion is prportional to the charges.
What is the netto force between the ISS and a supply ship?
Between the dust particles the repulsion is the winner.
S*


  #9  
Old December 12th 12, 10:48 PM posted to uk.sci.astronomy
Newshound
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Posts: 38
Default Planet's density

On 12/12/2012 09:04, Szczepan Bialek wrote:

The only "cause" of the metal core is the calculated density 5.5.


No, a metal core rather helps to explain the magnetic field. Plus,
analysis of earthquakes
gives good information on internal structure of the earth.

And we have had similar sensors on the moon, confirming the absence of a
metal core. One
of the surprises from the Apollo programme was how little "damping"
there was for lunar
vibrations set up by deliberately crashing the orbiter.
  #10  
Old December 13th 12, 09:17 AM posted to uk.sci.astronomy
Szczepan Bialek
external usenet poster
 
Posts: 51
Default Planet's density


"newshound" napisal w wiadomosci
eb.com...
On 12/12/2012 09:04, Szczepan Bialek wrote:

The only "cause" of the metal core is the calculated density 5.5.


No, a metal core rather helps to explain the magnetic field.


Some years ago Rowland proved that rotaing charged body create the magnetic
field.
The Earth has the excess of electrons and must have the magnetic field
because is rotating.

Plus, analysis of earthquakes
gives good information on internal structure of the earth.

And we have had similar sensors on the moon, confirming the absence of a
metal core.


The Moons do not rotate and there no magnetic field.

One
of the surprises from the Apollo programme was how little "damping" there
was for lunar
vibrations set up by deliberately crashing the orbiter.


The Moon is cold. The damping is temperature dependent.
S*


 




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