Crab nebula

History of Astronomy

  • 150

    Ptolemy

    Geocentric theory. Dates from this point forward are after Christ. This particular date is approximate.
  • 155

    Hipparchus

    Discovery of procession of equinoxes. Date is an estimation of time sometime before christ existed.
  • 250

    Eratosthenes

    First calculation of earth's circumfrence. B.C.E
  • 270

    Aristarchus

    First proposition of heliocentric universe and first calculations of distance of sun and moon. Before Christ existed.
  • 350

    Aristotle

    Discovers that earth is as phere and universe is infinite. Before Christ existed.
  • Jan 1, 1543

    Nicolas Copernicus

    Sun centered universe. (Heliocentric)
  • Johannes Kepler

    Three laws of planetary motion. Planets run along elliptical paths.
  • Galileo

    Construction of first complete telescope.
  • Giovanni Cassini

    first approximation of our solar systems dimensions. First to observe saturn's moons.
  • Christiaan Hugens

    Wave theory of light published.
  • Issac Newton

    Laws of motion and universal gravitation.
  • Albert Einstein

    General theory of relativity states effects of acceleration and gravity on time in space.
  • Big Bang

    Explosion of single particle is believed to cause ever expanding universe. Theory is still being refined to this day.
  • Stonehenge (BEFORE CHRIST EXISTED)

    Rock alignment suggests that it could have been specifically constructed to predict lunar and solar eclipses. Before Christ existed.