Ancient Astronomers

By gmessick
  • 276 BCE

    Eratosthenes

    Bc. 276 BC–192 or 194 BC), used geometry to calculate the circumference of the Earth. He is also known as the Father of Geography. You can read more about him in Measuring the Earth.
  • 168 BCE

    Claudius Ptolemy

    Set up a model of the solar system in which the sun, stars, and other planets revolved around Earth.
  • 1473

    Nicolaus Copernicus

    Proposed a model of the solar system that involved the Earth revolving around the sun. 1473 - 1543
  • 1546

    Tycho Brahe

    1546-1601 - known for his comprehensive and unprecedentedly accurate astronomical oberservations. He was the last major astronomer before the invention of the telescope.
  • 1571

    Johannes Kepler

    1571-1630 - Determined that planets traveled around the sun not in circles, as Copernicus had thought, but in ellipses. In so doing, he calculated three laws involving the motions of planets that astronomers still use in calculations today.

  • Sir Isaac Newton

    1643-1727 - is most famous for his work on forces, specifically gravity. Building on the work of those who had gone before him — he is quoted as saying, "If I have seen further, it is by standing upon the shoulders of giants" — he calculated three laws describing the motion of forces between objects, known today as Newton's laws.

  • Albert Einstein

    1879-1955 - became one of the most famous scientists ever after proposing a new way of looking at the universe that went beyond current understanding. Einstein suggested that the laws of physics are the same throughout the universe, that the speed of light in a vacuum is constant, and that space and time are linked in an entity known as space-time, which is distorted by gravity.