The original hypothesis for orbital dynamics is that larger celestial objects impart rotation on the smaller objects orbiting them, as Kepler noted.

"The Sun and the Earth rotate on their own axes...The purpose of this
motion is to confer motion on the planets located around them; on the
six primary planets in the case of the Sun and on the moon in the case
of the Earth. On the other hand, the moon does not rotate on the axis of
its own body, as its spots prove " Kepler

The magnetic fields need to be more utilized in exposing this component relating to the magnetic field due to daily rotation with the orbital field created by the Sun's rotation.

https://previews.123rf.com/images/shooarts/shooarts1507/shooarts150700004/42063279-planetary-magnetic-fields-realistic-colored-poster-vector.jpg

Many more considerations are involved; however, these outlines present a point of departure.

On Friday, October 20, 2023 at 4:21:57 AM UTC-7, Gerald Kelleher wrote:
> The original hypothesis for orbital dynamics is that larger celestial objects impart rotation on the smaller objects orbiting them, as Kepler noted.
>
> "The Sun and the Earth rotate on their own axes...The purpose of this
> motion is to confer motion on the planets located around them; on the
> six primary planets in the case of the Sun and on the moon in the case
> of the Earth. On the other hand, the moon does not rotate on the axis of
> its own body, as its spots prove " Kepler
>
> The magnetic fields need to be more utilized in exposing this component relating to the magnetic field due to daily rotation with the orbital field created by the Sun's rotation.
>
> https://previews.123rf.com/images/shooarts/shooarts1507/shooarts150700004/42063279-planetary-magnetic-fields-realistic-colored-poster-vector.jpg
>
> Many more considerations are involved; however, these outlines present a point of departure.

Kepler was obviously wrong about the moon not rotating on its axis.

On Friday, October 20, 2023 at 9:58:33 AM UTC-6, palsing wrote:

> Kepler was obviously wrong about the moon not rotating on its axis.

I would be much kinder to him than that.

Kepler is wrong _by modern standards_ when he says that the Moon doesn't rotate
on its axis.

Today, photography has allowed astronomers to study the Moon's libration in
detail. So we know that the Moon's libration in longitude is consistent with the
Moon rotating at a uniform pace, with the same period as its orbital motion,
with the libration being the result of the difference between that uniform motion and
its non-uniform orbital motion (as the Moon's orbit is both elliptical and inclined to
its Equator).

The naive view that a tidally-locked satellite is one that doesn't rotate isn't an
idiosyncracy of Oriel36. It's a perfectly normal way of thinking for a layperson.
The reasons why it's necessary to be more careful about this sort of thing, and
to define "rotation" in terms of the fixed stars (or, in some cases, at least some
other inertial frame) only became apparent with Isaac Newton.

So it's hardly reasonable to attach any blame to Kepler, and it's not surprising
that this view persists to the present day among naive laypeople. What's unusual,
however, is that when people are exposed to the reasons why the modern definition
of rotation is needed, for someone then to reject it to the extent of advancing
arguments that the naive definition is "right". The way Oriel36 is doing, and the way
one "S. V. V." did in _Considerations on the Established Doctrines concerning the
Moon's Rotation..._, or James Laurie did in his essay on the subject, or Henry
Perigal did in _The Moon Controversy_.

We can be thankful that this sort of thing is now very rare and unusual, and that
instead most people who are intelligent enough to even be exposed to the issue are
also intelligent enough to understand the reasons behind the modern approach to
the rotation of celestial bodies, but that doesn't mean that such an understanding is
easy and natural. It is the result of the accomplishment of Isaac Newton in creating
a modern science of mechanics, and of the prevalence of sound scientific education
in our modern age. (Which, incidentally, seems sadly to be on the decline, at least
somewhat, in the United States.)

What may seem obvious to those of us steeped in the perspective of modern
physical science is by no means "obvious" in an inherent sense. Were the Moon's
rotation so "obvious" as to occur naturally even to an untutored savage, the
Copernican theory would never have encountered the resistance it did when first
proposed.

John Savard