Hey again...another question...does mars have an electromagnetic field?..im debating against my roommate...he says mars doesnt have one because it's "frozen" solid..i disagree...i say every object in space has one. agree?

An electromagnetic field? If you are refering to a magnetic field (magnetosphere) Mars has a weak one. Mercury, Saturn, Jupiter and
Neptune have magnetospheres also. Venus, a hot, rocky planet, does
not have one.

Any planet with a fair amount of ferrous metal will probably develop a magnetic polarity after a few billion years.

Now that I've said that so confidently, what's the mechanism? My tools get magnetized because I keep pounding them in the vicinity of the earth's magnetic field and the molecules have more reinforcement to align magnetically along the longer axis, such as in a screwdriver or a wrench.

But how did the earth develop its magnetic field in the first place? Sure it underwent a lot of pounding with the tectonic plates and everything, but without a nearby magnetic field what would be the impetus for alignment? Does merely spinning accomplish it? I'm sure that magnetic fields attenuate so starkly that for all practical purposes no planet is really affected by the magnetic field of the sun or the other planets.

Hmmm. Anybody know the answer?

I don't know the answer, but I am aware of the "accepted" theory of earth's magnetic
field. The earth's core is thought to be a solid sphere surrounded by a liquid mantel
and then the crust on top of that. The earth's magnetic field is thought to be caused
by a difference in the speed of rotation between the core and the crust. I know the
sun's magnetic field and possibly the planets composed of gases (do any have a solid
core?) would have to use a different mechanism, though.

Another thing I wonder about. Venus has a retrograde (reverse) rotation and has no
magnetic field. Could there be a connection not recognized by mainstream physics?

>>But how did the earth develop its magnetic field in the first place? Sure it underwent a lot of pounding with the tectonic plates and everything, but without a nearby magnetic field what would be the impetus for alignment?

Not sure if this is the primary reason that initiated a magnetic field, but a little known cause for magnetic fields in rotating neutral massive bodies ( Blackett Effect ) may be one of the reasons.
Another possibility could be naturally occurring electrical current flow creating magnetic moments.

Mars doesn't have a magnetic field, but it did have one, four billion years ago.
The remnants of this magnetic field can be detected in the rocks, from orbit and on the ground,
Interestingly the giant crater Hellas was formed after Mars lost it's magnetic field, and the rocks there show no magnetic alignment.

How did it lose its field? Simply, by cooling down. The magnetic field of the Earth, and of ancient Mars is/was caused by rotation within the molten core; the core of Mars is much smaller, and only took 600 million years to cool so much that the dynamo effect disappeared.

Once that happened, Mars was at the mercy of the solar wind; the most dramatic solar gusts that hit Mars were able to carry away some of the atmosphere, a process known as 'sputtering'.

If we are ever to terraform Mars, we will need to compensate for the loss of the magnetosphere;
here is my fictional 'Lagrange Magshield', a device designed to avert the worst solar storms away from Mar's surface...
no idea if it would work, but something similar will be required eventually.

__________________
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From what I read, Mars doesn't have a magnetosphere like the earth's,
but it does still have a magnetic field in the southern hemisphere which
extends hundreds of miles above the surface. Since the field doesn't
protect the atmosphere of the entire planet, it would not be possible to
have a dense atmosphere on Mars, but you would be protected from the
solar wind if standing underneath it. In those areas, the magnetic field
is as strong as the earth's. Also, the earth's core is thought to be solid,
either iron or nickel-iron, and is kept solid by the intense pressures in the
center of the earth. It rotates faster than the crust, gaining about one
revolution more than the crust every 400 years.
About the magnetic field of Mars:
http://science.nasa.gov/headlines/y2001/ast31jan_1.htm
About earth's solid core:
http://www.innerx.net/personal/tsmith/coreLDCol.html

Another thing I wonder about. Venus has a retrograde (reverse) rotation and has no
magnetic field. Could there be a connection not recognized by mainstream physics?

Planetary magnetic fields are believed to be generated by the dynamo effect of rotation within a conductive liquid core or mantle. Earth has its molten nickel-iron outer core. Jupiter and Saturn have huge mantles of liquid metallic hydrogen, which is a superconductor, explaining the enormous extent and intensity of their magnetospheres.

Venus probably has a very similar internal structure to Earth, with a molten iron layer - however, it rotates only once every 243 terrestrial days. This very slow rotation rate is the reason for the absence of a magnetic field; the direction of rotation need not matter.