Timeline of universe ideas

  • 150

    Ptolemy

    Ptolemy perfected the geocentric model in "Almagest" which listed 48 constellations, and documented the epicycles of celestial objects.
  • 1543

    Copernicus

    Copernicus wrote "On the Revolution of Celestial Spheres" explaining a heliocentric universe and retrograde motion.
  • 1576

    Brahe

    Tycho Brahe combines the geocentric and heliocentric theories to form his own Tychonic Model.
  • Kepler

    Upon discovering the planets orbit around the Sun, Kepler proposed his three laws of planetary motion: 1. Planets move in an elliptical orbit 2. Planets move an equal area of space in equal amounts of time 3. P^2 = a^3
  • Galileo

    Galileo first uses a refracting telescope and observes that the sun and moon are not perfect spheres, sunspots rotate, the 4 moons of Jupiter, and that Venus has phases. He also defends the heliocentric theory.
  • Einstein

    Einstein‘s theory of special relativity suggests nothing can travel faster than the speed of light which proposed new concepts of space and time.