How was it first determined that Earth orbits the Sun?

1543 - Nicolaus Copernicus - Copernican theory

I could go into the how but armed with its name you can find many explanations that would be more thorough.

Here's one: http://es.rice.edu/ES/humsoc/Galileo/newsite/galileo/sci/theories/copernican_system.html

I believe that the Greeks came up with the idea long before Copernicus. I would suggest that Copernicus be offered as the source for the "re-introduction" of the concept.

However, i don't recall to whom i should refer you. Perhaps to Anaxamander, or Pytheas, or perhaps Callippus. Good question, Boss, because all of this refers to "the western world." Other civilizations were obsessed with astronomy as well, and i don't feel well enough informed to say that none of them did not demonstrate the principle.

Yes, I just found Copernicus, but I haven't yet read how he arrived at his conclusions. I'll read your link.

Also, was Copernicus the *first* to recognize the heliocentric system, or did older cultures show evidence of it as well? I'm wondering about the Aztecs and Inca's and such.

Thanks,

Among the tribes of central America, i'd say you'd find more information on astronomical investigation among the Maya.

Also, check out Hindu cosmology, as well as the island of Bali. I'm not certain about the ancient Chinese--although i know they practiced astronomy, i don't know the details.

Hmm, I recall vaguely being told that other cultures had heliocentric theories but I remember thinking that they wer as arbitrarily come upon as the geocentric one.

I don't think the Copernican theory really established it either. I think there was subsequent turning points.

Hmm, now you have me curious too. If you find the answer about the *how* please share it with us.

my memory is weak but Ptolemy rings a bell in me head.

Yes, I saw your post after mine went in... this is also what I was wondering.



Yes, the *how* part is really what I'm curious about.

Some of the web links I've perused seem to indicate that it was a "collective" discovery which derived from observations of other planetary motions (such as Jupiter's moons by Galileo).

I'm still searching...

Why don't you try googling "heliocentric theories" or something to that effect. I'd be happy to oblige you myself, but i'm lazy as sin, and twice as much fun.

Excellent question, btw, Boss . . . it's always good when you set this crowd to wondering . . .

Actually my girlfriend asked me this the other day and I couldn't answer it. And right when I was playing Mr. Know-it-all in astronomy too, serves me right

She asked me how it was first discovered, and after a bit of um... well... uh, I had to admit that I didn't know. All I could remember was someone (Galileo I think) observing sailing ships through telescope and noticing that the masts appeared first before the bow. But this was how the Earth was confirmed to be not flat, it wasn't how Heliocentricity was determined.

um thinking the "reseach" was originally done in Egypt with measured distances and shadow lengths.

In surveying we were taught that Aristarchus first developed a rigorous proof of a sun centered relationship. he was shot down because his proofs were not able to be tested. I remember that one argument was
"If the earth moves and you throw something strait up in the air , it will land in a different spot" QED ok Aristarchus youre wrong.
I think it was like 300BC. Look up Aristarchus of Samis

[In about 270 B.C., Aristarchus of Samos proposed the helicentric model of solar system, which correctly placed the Sun at the center with Earth and the other planets revolving around it. He reashed his conclustion after estimating the relative sizes of Earth, the Moon, and the Sun and discovering that the Sun was much larger than Earth. But the idea was disregarded until nearly 1,900 years later, largely because of the strength of the prevailing geocentric belief, based on Greek Philosophy and religion, that Earthitself was the center of the solar system.]

Source: http://spacediscovery.8m.com/history

[Written records, observatories, monuments, measuring instruments, and other artifacts show that most ancient civilizations not only studied the skies, but did so with considerable accuracy.The Summerians, Babylonians, Egyptians, and Chinese made the first known recorded measurements of the stars and the movement of the planets.
By about the fifth century B.C., Babylonians had identified the region of sky through witch the Sun, Moon, and plantes move as viewed from Earth, and they had named several "planet gods" visible to the human eyes - the Sun, Moon, Mercury, Venus, Mars, Jupiter, and Saturn (the basis of out names for the seven days of the week).]

Considering ancient structures like Stonehenge and some American Indian astronomical sites, I also wonder if they realized the true structure of the solar system, but never recorded the knowledge.

Thanks Farmerman. We posted at almost the same time

I've always wondered how Avagadro found his number. I have fantasies involving Mrs. Avagadro sitting around counting molecules.

The buddhists from India studied the earth's path around the sun. The ancients built Angkor Wat in Cambodia with mathematical accuracy and intracacy.

Forgive my perversity here but I always understood that the heliocentric system was preferred because it made the equations simpler. There is no "objective truth" and in "fact" the Sun and Earth could be considered to rotate about a common centre of gravity. This is case where "elegance" is utilized in choice of explanation.

So in my book the question is not how but why.

Galileo discovered that sunlight moved across other planets like it did on Earth. This meant that all the planets including the Earth must orbit the sun. I think that's about the earliest "proof" of the heliocentric model but it took a lot of work by Kepler and then Newton before it was widely accepted.