听写训练营Day31

1. Ok, we have been talking about how throughout history, it was often difficult for people to give up ideas which have long been taken for granted as scientific truth, even if those ideas were false, in astronomy, for example, the distinction between the solar system and the universe wasn’t clear until modern times, the ancient Greeks believed that what we called the solar system was in fact the entire universe, and that the universe was geocentric. 

2. Geocentric means Earth-centered, so the geocentric view holds that the sun, the planets, and the stars, all revolve around the earth, which is stationary, of course, we now know that the planets, including earth, revolve around the sun, and that the solar system is only a tiny part of the universe, so why did the ancient Greeks believe that the earth was the center of the universe? Well, it made sense to them. 

3. Observations of the sky make it appear as if the sun, the moon, and the stars all revolve around the earth everyday, while the earth itself stayed in one place, and this view is also supported by their philosophical and religious beliefs about the origin and structure of the universe, it was presented in the works of well-known Greek philosophers as early as the fourth century BCE, and the geocentric theory continue to prevail in Western thought for almost 2,000 years, until the 17th century.

4. Now, what’s especially interesting is that when astronomical observations were made that seemed to be inconsistent with the geocentric view, the ancient Greeks did not really consider alternative theories, it was so intuitive, so sensible that the earth was the center of the universe that astronomers found ways to explain those seemingly inconsistent phenomena within the geocentric view.

5. The geocentric theory said that the planets would move around the earth in one direction, however, astronomers noticed that at times, several planets seem to stop moving in one direction and start moving backward in their orbits around the earth, and they came up with a theory that these planets themselves moved in smaller circles called epicycles as they travelled around the Earth.