Our Understanding of the Universe

  • Period: 100 to 168

    Ptolemy

    On the motions of the Sun, Moon, and planets, Ptolemy again extended the observations and conclusions of Hipparchus--this time to formulate his geocentric theory, which is popularly known as the Ptolemaic system.
  • Period: 1473 to 1543

    Copernicus

    Copernican heliocentrism is the name given to the astronomical model developed by Nicolaus Copernicus and published in 1543. It positioned the Sun near the center of the Universe, motionless, with Earth and the other planets rotating around it in circular paths modified by epicycles and at uniform speeds.
  • Period: 1564 to

    Galileo

    Image result for galileo theory
    In 1632, he published a book that stated, among other things, that the heliocentric theory of Copernicus was correct. Galileo was once again called before the Inquisition and this time was found guilty of heresy. Galileo was sentenced to life imprisonment in 1633.
  • Period: 1571 to

    Kepler

    Kepler's work (published between 1609 and 1619) improved the heliocentric theory of Nicolaus Copernicus, explaining how the planets' speeds varied, and using elliptical orbits rather than circular orbits with epicycles.
  • Period: to

    Newton

    ewton's law of universal gravitation ↑ Newton's law of universal gravitation states that every mass attracts every other mass in the universe, and the gravitational force between two bodies is proportional to the product of their masses, and inversely proportional to the square of the distance between them.