Discovery of Elliptical orbits

[Mike Dworetsky]

Who was first to "know" or theorize that the planets'
orbits were ellipses? Kepler's discovery is treated as
an important key to the Scientific Revolution, but
Aryabhatta (476-550) and Franciscus Vieta (1540-1603)
were both said to have realized the fact earlier.
Knowing the Sun is not the center of the orbit, would
one be intuitively surprised to learn the orbit is a
perfect ellipse rather than some less symmetric oval?
Is it possible that Aryabhatta and Vieta only knew that
the orbits weren't perfect circles rather than "knowing"
they were perfect ellipses?
That Kepler determined the ellipses from observational
data without modern methods and machines seems impressive.
Did Aryabhatta and Vieta base their conclusions on
observation or theory?
James D. Allen

I doubt very much that any earlier writer "knew" that the orbits were
ellipses. They certainly could not have known from observations. So
if they actually said this, they were guessing. On the other hand, the
idea of the eccentric or offset circle (where the centre of motion is
not the centre of the circle) was very well known even in Ptolemaic
systems as a computational expediency. Did they have fully developed
heliocentric theories?
Kepler's achievement does not merely seem impressive--it is very
impressive!

You doubt very much that Kepler "knew" that the orbits were ellipses.
You say
he certainly could not have known from observations. So if he actually
said
this, he was guessing.
Your reasoning does not merely seem unimpressive--it is very
unimpressive!
Idiot!

No, I am referring to those two earlier pre-Keplerian writers mentioned,
which is what the OP asked about. Kepler did not "know" about ellipses
either, until he tried them against the Tychonic observations. You might
say that ellipses were the very last thing he came up with in his quest.
I know you are a moron who cannot read a simple post for comprehension.
You are also very ignorant of the history of astronomy, but get immense
pleasure out of inserting your own erroneous readings or interpretations
into your replies.
I am making an exception to my usual rule of not replying to your posts.

Your logic is truly underwhelming, on a par with your intelligence.
According to Dworetsky only Tycho Brahe can make Brahean observations
and only Johannes Kepler can figure out a Johannic orbit is elliptical.
I am not making an exception to my usual rule of plonking fuckin' idiots
like you.
*plonk*
Do not reply to this generic message, it was automatically generated;
you have been kill-filed, either for being boringly stupid, repetitive,
unfunny, ineducable, repeatedly posting politics, religion or off-topic
subjects to a sci. newsgroup, attempting cheapskate free advertising
for profit, because you are a troll, simply insane or any combination
or permutation of the aforementioned reasons; any reply will go unread.
Boringly stupid is the most common cause of kill-filing, but because
this message is generic the other reasons have been included. You are
left to decide which is most applicable to you.
There is no appeal, I have despotic power over whom I will electronically
admit into my home and you do not qualify as a reasonable person I would
wish to converse with or even poke fun at. Some weirdoes are not kill-
filed, they amuse me and I retain them for their entertainment value
as I would any chicken with two heads, either one of which enables the
dumb bird to scratch dirt, step back, look down, step forward to the
same spot and repeat the process eternally.
This should not trouble you, many of those plonked find it a blessing
that they are not required to think and can persist in their bigotry
or crackpot theories without challenge.
You have the right to free speech, I have the right not to listen. The
kill-file will be cleared annually with spring cleaning or whenever I
purchase a new computer or hard drive.
I hope you find this explanation is satisfactory but even if you don't,
damnly my frank, I don't give a dear. Have a nice day.

In other words, you are a twit with no manners and no knowledge and
learning, pretending to be a great pundit. By the way, everyone knows it.

It's funny though: Brahe was the first sufficiently accurate observer of
stellar and planetary positions, so yes he was the only one who could make
Brahe's observations, and Kepler was the one who first demonstrated that
planetary orbits are ellipses using those observations. Nobody else before
him did this. As usual, the ill-mannered Androcles (who hides behind a
pseudonym) can't even work this out.

Of course if Androcles has truly "plonked" me he will never see this, which
I don't really care about at all.

[Peter Webb]

Who was first to "know" or theorize that the planets'
orbits were ellipses? Kepler's discovery is treated as
an important key to the Scientific Revolution, but
Aryabhatta (476-550) and Franciscus Vieta (1540-1603)
were both said to have realized the fact earlier.
Knowing the Sun is not the center of the orbit, would
one be intuitively surprised to learn the orbit is a
perfect ellipse rather than some less symmetric oval?
Is it possible that Aryabhatta and Vieta only knew that
the orbits weren't perfect circles rather than "knowing"
they were perfect ellipses?
That Kepler determined the ellipses from observational
data without modern methods and machines seems impressive.
Did Aryabhatta and Vieta base their conclusions on
observation or theory?
James D. Allen

I doubt very much that any earlier writer "knew" that the orbits were
ellipses. They certainly could not have known from observations. So
if they actually said this, they were guessing. On the other hand, the
idea of the eccentric or offset circle (where the centre of motion is
not the centre of the circle) was very well known even in Ptolemaic
systems as a computational expediency. Did they have fully developed
heliocentric theories?
Kepler's achievement does not merely seem impressive--it is very
impressive!

You doubt very much that Kepler "knew" that the orbits were ellipses.
You say
he certainly could not have known from observations. So if he actually
said
this, he was guessing.
Your reasoning does not merely seem unimpressive--it is very
unimpressive!
Idiot!

No, I am referring to those two earlier pre-Keplerian writers mentioned,
which is what the OP asked about. Kepler did not "know" about ellipses
either, until he tried them against the Tychonic observations. You might
say that ellipses were the very last thing he came up with in his quest.
I know you are a moron who cannot read a simple post for comprehension.
You are also very ignorant of the history of astronomy, but get immense
pleasure out of inserting your own erroneous readings or interpretations
into your replies.
I am making an exception to my usual rule of not replying to your posts.

Your logic is truly underwhelming, on a par with your intelligence.
According to Dworetsky only Tycho Brahe can make Brahean observations
and only Johannes Kepler can figure out a Johannic orbit is elliptical.
I am not making an exception to my usual rule of plonking fuckin' idiots
like you.

No, that is not what he said.

You were wrong in your previous post; he was quite explicit ...

"I doubt very much that any earlier writer [than Kepler] "knew" that the
orbits were ellipses."

You simply misread and misquoted him.

Now you are inventing things he never said.

You first post, I put down to stupidity; the second one (where you just
invent things the poster didn't say) I put down to malice.

Neither demonstrates any comprehension or understanding of either physics or
its history. You should be thanking the poster for teaching you something
you obviously didn't know.

HTH