wrote:

Marshall Dudley wrote:

There are many problems with that hypothesis. First of all there is no
interaction between photons and a magnetic field. Secondly photons
present a pressure, not an attraction.

I have a better idea.

As the planet circles the sun, there is coupling of the iron core to the
sun's magnetic field. (Yes the iron core is not ferromagnetic due to the
heat being over the curie temperature, but there is still coupling due to
it being conductive and the associated electrical eddy currents).

(snip)

Why is there any need for input of energy from an external source to
"keep planets rotating"?

Conservation of angular momentum does the job quite nicely....

Simple. It is called the second law of thermodynamics.

The tides get their energy from the rotation. Most is dissapated through
friction and heat, but there are some areas that use damns to pull energy from
the tides and generate energy. This causes tidal braking, which slows the
rotation of the earth down according to theory. Of course angular momentum
must be conserved as well. With the moon, the earth loses rotational energy,
but the moon gains exactly the same amount of angular momentum, so the total
system angular momentum is unchanged. With the sun as a source of the tides
any loss of angular momentum is compensated for via momentum being transferred
to the sun, and/or the earth's orbit.

Marshall