Bill Sloman <bill.sloman@ieee.org> wrote:Earth has a magnetic field, and nobody uses magnets to drag boats or
aircraft around.
Earth *is* a magnet.
You could say that, *because* it has a (non-zero) magnetic field (not
vice-versa). An object is not a magnet /per se/.
It is pushed by the magnetic fields of the sun and galaxies.
Not enough.
That's what makes the earth go round the sun.
No, that's nonsense. The best explanation that we have for that is
_gravitation_. Gravitation is NOT the same as magnetism.
Terra (Earth) orbits the barycenter of the Sol System because it formed from
a rotating planetary disk. That disk was rotating because it formed from
the rotating part of a molecular cloud at the same time as Sol (the Sun)
formed; it was what was left over from the star's formation (the star formed
because that part of the cloud had cooled enough by emitting radiation, and
was dense enough so that gravitation caused it to collapse on itself; the
collapse caused its density to increase further, and its temperature to
increase again, eventually that much that nuclear fusion became possible and
likely). That piece was rotating, because small imbalances in mass (perhaps
supported by a nearby supernova) cause particles of a molecular cloud to
move in different directions, and when they become too close, they begin to
orbit each other (or rather their common barycenter) due to gravitation.
This is not just a story or a model anymore because we can observe it in the
formation of other stars and their planetary systems.
F'up2 sci.astro
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