He backed up the theory with empirical observation and was the first person to prove that the earth was indeed round. He observed a lunar eclipse (when the Earth casts its shadow on the moon) and noticed that the shadow of the earth on the moon was curved. As only a round object could cast a curved shadow, it could be inferred that the earth was round. (Fowler)
Aristotle theorized that not only was the earth the center of the universe, it was stationary in contrast to other planets. He "proved" this theory by stating that if the earth was moving, an observer on it would see the fixed stars as moving, just as he can see the planets moving. Since this is not the case, Aristotle deducted that the earth must be at rest. This theory about the earth being stationary and the center of the universe remained an accepted fact for centuries before Galileo and Copernicus proved it wrong through more scientific observation.
In Astronomy, Aristotle accepted the theory prevalent at the time that there were four basic elements -- earth, air, fire and water and proposed that the central region of the universe was composed of these four elements. He, however, added the theory that the celestial bodies (the heavens) were made of a fifth element called aether which was eternal and unalterable. It was found in the purest form in the outermost (celestial) regions but was contaminated in the region below the moon.
Aristotle's theory of motion is rather complicated and has been interpreted in different ways. He used this theory to explain the movement of objects on the earth and beyond. According to Aristotle, the universe consists of two distinct worlds -- the sub-lunar which was always changing and in which objects moved in rectilinear motion and the super-lunar, the world of the unchanging celestial eternal bodies (made of aether) that moved in a circular motion. He further maintained that the four elements of the sub-lunar world tend to move in straight lines but the direction of their movement would depend on their specific gravity, i.e., the earth being heavy would move downward, fire upward, and water and air would hang in between.
Aristotle also believed that the objects...
The universe viewed through a telescope looked different, and this difference in itself played into the Protestant argument that received truths may be fallible. In fact, the notion of truth outside empirical evidence became unsteady: For most thinkers in the decades following Galileo's observations with the telescope, the concern was not so much for the need of a new system of physics as it was for a new system of
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