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User: When was the theory of galaxies first developed ? Were there any astronomers outside Europe who came up with the basic idea before Thomas Wright ?
ChatGPT: The concept of galaxies as large systems of stars was first proposed by the English astronomer Thomas Wright in his book "An Original Theory or New Hypothesis of the Universe" in 1750. Wright's idea was that the Milky Way was a flat disk of stars that could be seen edge-on from our vantage point on Earth, and that other similar systems of stars existed beyond the Milky Way.

While there were no astronomers outside Europe who developed the concept of galaxies before Thomas Wright, there were some ancient Greek philosophers who speculated about the nature of the Milky Way. For example, in the 4th century BCE, Democritus proposed that the Milky Way was made up of a vast number of stars, while Aristotle in the 3rd century BCE suggested that the Milky Way was made up of a combination of light from many stars and the celestial sphere. However, these early ideas did not fully develop into the concept of galaxies as we understand them today.
User: What did non-European astronomers think galaxies were?
ChatGPT: Non-European astronomers throughout history had various ideas about the nature of celestial objects that we now know as galaxies, although they did not use the term "galaxy" as we do today.

In ancient China, for example, astronomers observed a band of faint light in the sky that they called the "Celestial River." This was likely a reference to what we now call the Milky Way, although it is unclear if they understood it to be a vast system of stars.

In the Islamic world, astronomers such as Alhazen and Ibn al-Shatir proposed models of the universe that incorporated the idea of concentric spheres, with the Earth at the center and the stars arranged on different layers of spheres. However, they did not propose a concept of galaxies as we know them today.

In India, the astronomer Aryabhata proposed a model of the universe in the 5th century CE that was centered on the Earth and included a description of the Milky Way as a "streak of light." However, this was not a fully developed concept of galaxies.

It wasn't until the 20th century, with the advent of more advanced telescopes and the work of astronomers like Edwin Hubble, that the concept of galaxies as vast systems of stars became firmly established in astronomy.