Well, at least of our understanding of it. While books such as "Let There
be Light" by Rudolf Thiel deal with this fascinating story at greater
length, along with the history of the rest of astronomy, I have condensed
the story into a few short paragraphs (I see, though, that I should have spared
a sentence or two on the discovery of the asteroids...) as follows:

"In ancient times, astrology dealt with seven bodies; the two Luminaries,
the Sun and the Moon, and the five Planets, Mercury, Venus, Mars, Jupiter
and Saturn.

"By the time of Ptolemy, it was recognized that the Earth was a sphere
rather than a small flat disk, but the planets and luminaries were still
thought of as revolving around the Earth at the center.

"The first step in expanding our conception of the Solar System was, of
course, taken by Nicolaus Copernicus, who proposed that the Earth went
around the Sun instead. Galileo saw the moons of Jupiter in his telescope,
which made the Copernican theory more plausible, and in his writings set
forth a persuasive defense of that theory. Kepler then took astronomy
further away from Ptolemy, by replacing epicycles with elliptical orbits
following the law that equal areas were swept out in equal times.

"Finally, Isaac Newton established that an inverse square law for the
gravitational force, followed by the ordinary physical laws of mechanics,
would lead to the planetary motions described by Kepler. By giving a
physical basis to Solar System phenomena, he ended the era when the
heliocentric theory was something that could be credibly debated.

"Newton's explanation of the Solar System in physical terms opened up a
large vista of new possibilities. Pierre-Simon de Laplace, in his Traité de
Mécanique Céleste provided the mathematical tools with which to study
how the planets departed from strictly following Kepler's Laws because
their masses, while much smaller than that of the Sun, were still not
utterly negligible, and so the orbits of planets were also slightly affected
by the gravitational attraction of other planets, leading to perturbations.

"In 1781, shortly before the publication of Laplace's book began, Sir
William Herschel observed Neptune, eventually coming to the conclusion
that it was not merely a comet, but was actually a new planet.

"Studies of the motion of the new planet Neptune led to the conclusion
that its motion could not be exactly accounted for due to perturbations
from the existing planets, primarily Jupiter and Saturn. Both the French
astronomer Urbain Le Verrier and the English astronomer John Couch
Adams made calculations which led to an accurate prediction of the
position of Neptune; but as it was Le Verrier who was able to secure
telescopic observations to confirm his prediction, he, and the observer
Johann Gottfried Galle, are credited with the discovery of Neptune.

"In turn, the motion of Neptune was studied in hopes that it might lead to
the discovery of further planets beyond it. For a time, it seemed that there
were unaccounted-for perturbations of both Uranus and Neptune which
did point to the existence of an additional planet, dubbed "Planet X". The
astronomer William Henry Pickering was one of the leaders in carrying out
these calculations.

"This eventually led to the telescopic search for the new planet which
culminated in the discovery of Pluto. However, there were doubts about
whether or not Pluto was actually massive enough to account for the
perturbations which started the search that led to its discovery. After
Pluto's moon, Charon, was discovered in 1978, it was proven that Pluto
had nowhere near enough mass to significantly affect the orbits of
Uranus and Neptune.

"The astronomer Robert Harrington continued the effort to find Planet X
by calculation, which had been left off after the discovery of Pluto, after
this; but in 1992, E. Myles Standish adjusted the mass of Neptune based
on data from the 1989 Voyager 2 flyby; the reduction in the mass of
Neptune this led to eliminated the need for an additional planet to explain
unknown perturbations.

"At the other end of the Solar System, the advance of the perihelion of
Mercury was greater, by 42 arc-seconds per century (being 574 arc-
seconds per century instead of 532 arc-seconds per century, which was
expected), than could be explained by the perturbations from the gravity
of the other planets. This led to a planet orbiting closer to the Sun than
Mercury, called Vulcan, being postulated. Eventually, however, it was
learned that not only was there no such planet, but that instead the
additional advance of the perihelion of Mercury could be accounted for by
a completely un-anticipated cause: the changes to the law of gravity
which resulted from Albert Einstein's General Theory of Relativity; this
factor implied that the perihelion of Mercury would advance by an extra
43 arc-seconds per century. (The one extra arc-second per century is
believed to be little enough that the uncertainties in our knowledge of the
motions of Mercury and the masses of other planets is enough to account
for it.)"

The main focus of the web page on which this text appears is
to list the most prominent members of the huge number of
asteroids, and of imaginary solar system bodies that had never
even existed at all, that were used by astrologers - and their
symbols for these bodies, as well as for signs and aspects, are
also shown on the page

http://www.quadibloc.com/other/as02.htm

John Savard

On Friday, September 23, 2022 at 12:00:29 AM UTC-6, Quadibloc wrote:
> (I see, though, that I should have spared
> a sentence or two on the discovery of the asteroids...)

Adding that allowed me to notice, and therefore correct an embarassing
blooper:

"In 1781, shortly before the publication of Laplace's book began, Sir
William Herschel observed Uranus, eventually coming to the conclusion
that it was not merely a comet, but was actually a new planet. In 1801,
Giuseppi Piazzi discovered Ceres; afterwards, other asteroids were
discovered in rapid succession. At first, these bodies were taken to be
new planets, but as the number of known asteroids grew, it was
eventually decided to place these smaller bodies in a different category.
Of course, this anticipates the fate that befell Pluto after the discovery of
Eris.

"Studies of the motion of the new planet Uranus led to the conclusion
that its motion could not be exactly accounted for due to perturbations
from the existing planets, primarily Jupiter and Saturn. Both the French
astronomer Urbain Le Verrier and the English astronomer John Couch
Adams made calculations which led to an accurate prediction of the
position of Neptune; but as it was Le Verrier who was able to secure
telescopic observations to confirm his prediction, he, and the observer
Johann Gottfried Galle, are credited with the discovery of Neptune."

I had written "Neptune" in both places where I was actually
referring to Uranus!

John Savard