From Newsgroup: alt.history.what-if

On 05/06/2025 16:52, pyotr filipivich wrote:

Charles Packer <mailbox@cpacker.org> on Wed, 28 May 2025 07:41:38
-0000 (UTC) typed in alt.history.what-if the following:

On Mon, 26 May 2025 08:58:20 -0700, pyotr filipivich wrote:

Charles Packer <mailbox@cpacker.org> on Mon, 26 May 2025 07:53:50 -0000
(UTC) typed in alt.history.what-if the following:

What if the moon wasn't tidally locked and humanity could see that it
was a rotating sphere? Would that have affected the history of
astronomy?

Yes.

How? Very hard to say.

What do you think would have happened?

I would think that it would have led to the heliocentric
conception of the solar system way earlier than Copernicus
if the rotation of the moon were asynchronous with its
revolution around the earth. The reason is that it would have
made the three-dimensionality of the cosmos obvious from
prehistory onward.

The moon rotates. How does that 'prove' that the earth is not the center of the universe?
The moon rotates, the "wanderering stars" (aka 'planets') wander,
and all of course circle the earth.

I recall reading that the Kepler model was adopted largely because
it made the math simpler for astronomers (who needed to set the
calendar).

It may make the premise that the Earth rotates more plausible. Putting
that into the model removes the diurnal motion of the Sun from it,
perhaps making the Keplerian model more obvious much earlier in history.

Anyway, the heliocentric theory was known and discussed almost 2000
years before Copernicus and Kepler made the concept popular once more.

Paul
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From Newsgroup: alt.history.what-if

On 5/26/25 00:53, Charles Packer wrote:

What if the moon wasn't tidally locked and humanity could see
that it was a rotating sphere? Would that have affected the
history of astronomy?

Tidal locking is a phenomenon in physics.

Supposedly the most common type of star in the
universe (the red dwarf, this phrase is based upon
a brown dwarf not actually being a star) has the
zone where solar energy is similar to that of Earth
is so close to the star that tidal locking will
generally make a planet in that zone always show
the same face to the star in a similar manner to
Earth's moon to Earth and a lot of the outer solar
system moons and the planets they revolve around.

The moon's revolution around the Earth however is
generally aligned with the ecliptic, or the orbits
of the planets around the Sun, and not the tilt of
the Earth's rotation. This might tend to make
eclipses more frequent. I guess it would not take
too much punching of a calculator or slide rule to
calculate how far out in orbit the Earth's moon would
need to be for tidal forces of the Sun to predominate,
however not be far enough for the Moon to get a
different orbit around the Sun than the Earth and
become another planet. The moons of Jupiter are
a similar distance from Jupiter as the Earth's moon
is from Earth, and so the Earth's moon could by
direct vision in theory be resolvable from Earth
anywhere in the inner solar system, however of
course one's eyes might start boiling without
a helmet because of vacuum.

Earth, Mars, Saturn, and Neptune have about a quarter
axial tilt, Mercury, Venus, and Jupiter have very little
axial tilt, and Uranus is generally on its side. This
generally tends to produce something like 'seasons' on
Earth at many latitudes with apogee and perigee generally
having lesser effects (sort of like Mercury for total
solar radiation input however Mercury has little or
no atmosphere). Galileo supposedly almost discovered
Neptune. He saw what appeared to possibly be a moving
star in an area he was looking at but thought he made a
mistake in an earlier drawing and did not think that what
he observed was actually moving. He did not look at the
object later based upon the idea that an earlier observation
was a mistake.



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