Hi, karshish-ga:
Let me point you first to a student paper:
[Aristarchus of Samos, by Kristen Riley]
http://www.perseus.tufts.edu/GreekScience/Students/Kristen/Aristarchus.html
which pulls together some nice links from a classics perspective.
First note the image she's posted of a manuscript page from
Copernicus's own heliocentric treatise, De revolutionibus caelestibus:
http://www.perseus.tufts.edu/GreekScience/Students/Kristen/Copernicus.gif
in which a passage, struck out prior to publication, says (in translation):
"Philolaus believed in the mobility of the earth, and some even say
that Aristarchus of Samos was of that opinion."
Copernicus's reasons for leaving this out in the published version of
his work will have to remain something of an unexplored by-path for
now.
Let's turn to the crux of your question, namely what grounds there are
for believing that Aristarchus (c. 310-230BC) proposed, not only that
the Earth moved, but that it moved in a circular orbit around the Sun.
It is true that a direct statement of this theory does not appear in
the one "surviving" work attributed to Aristarchus, On the Sizes and
Distances of the Sun and Moon. However as often happens with those
whose ideas found justification long after they lived, very convincing
evidence for those ideas is conveyed by the contemporaneous
disagreements that survive.
Such is the case here with Archimedes citation of Aristarchus. As Ms.
Riley has translated for us:
[Sand Reckoner, Chapter 1 by Archimedes]
http://www.perseus.tufts.edu/GreekScience/Students/Kristen/sand-reckoner.html
"Now you are aware that 'universe' is the name given by most
astronomers to the sphere the center of which is the center of the
earth, and the radius of which is equal to the straight line between
the center of the sun and the center of the earth; this you have seen
in the treatises written by astronomers. But Aristarchus of Samos
brought out writings consisting of certain hypotheses, in which it
appears, as a consequence of the assumptions just made, that the
universe is many times greater than the "universe" just mentioned. His
hypotheses are that the fixed stars and the sun remain unmoved, that
the earth revolves about the sun in the circumference of a circle, the
sun lying in the middle of the orbit, and that the sphere of the fixed
stars, situated about the same center as the sun, is so great that the
circle in which he supposes the earth to revolve bears such a
proportion to the distance of the fixed stars as the center of the
sphere bears to its surface."
It should be said that Archimedes goes on to reject this theory, and
that his tone though polite is one of equable disparagement.
Others were more vociferous in condemning the theory on what might be
described as religious or philosophical grounds. For example,
according a passage in Plutarch translated here:
[Plutarch, De facie in orbe lunae , c. 6]
http://www.perseus.tufts.edu/GreekScience/Students/Kristen/Plutarch.html
there was a Stoic philosopher who wanted Aristarchus tried:
"Only do not, my good fellow, enter an action against me for impiety
in the style of Cleanthes, who thought it was the duty of the Greeks
to indict Aristarchus of Samos on the charge of impiety for putting in
motion the Hearth of the Universe, this being the effect of his
attempt to save the phenomena by supposing the heaven to remain at
rest and the earth to revolve in an oblique circle, while it rotates,
at the same time, about its own axis."
In addition a quotation preserved in the writings of Theon of Symrna
attributed to Dercyllides (or Dercylidas, apparently mentioned by
Xenophon as a contemporary of Plato), who:
"says that we must suppose the earth, the Hearth of the House of the
Gods according to Plato, to remain fixed, and the planets with the
whole embracing heaven to move, and rejects with abhorrence the view
of those who have brought to rest the things which move and set in
motion the things which by their nature and position are unmoved, such
a supposition being contrary to the hypotheses of mathematics."
This opposition to a heliocentric model demonstrates at a minimum some
currency in philosophical circles of the time, if not the precise debt
to Aristarchus.
Finally we may indulge ourselves in a slight speculation about the
relationship between the heliocentric theory and the one surviving
work by Aristarchus. His calculations, which had a sound theoretical
basis though not free of measurement errors, showed the universe is
much bigger than his contemporaries contemplated, as Archimedes
prominently mentions. They also showed that because of its distance,
the Sun was really much bigger than the Earth or the Moon. It seems
that the notion of the Earth moving around the Sun may have been
motivated in part by the apprehension of how very much larger the Sun
is than the Earth.
regards, mathtalk-ga
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