Astronomy Timeline

By Albitaa
  • 4000 BCE

    Mesopotamian ziggurats serve as observatories.

    Mesopotamian ziggurats serve as observatories.
    Mesopotamian astronomers made careful observations from the tops of pyramid-like towers called ziggurats.
  • 2000 BCE

    Temple of Amen-Ra at Karnak.

    Temple of Amen-Ra at Karnak.
    Temple of Amen-Ra at Karnak. The Temple of Amen-Ra at Karnak, Egypt was built so that its main axis points to the sunset at the summer solstice.
  • 2000 BCE

    Lunar eclipse observed at Ur in Mesopotamia.

    Lunar eclipse observed at Ur in Mesopotamia.
    The oldest known recording of a lunar eclipse took place at Ur more than 4000 years ago.
  • 350

    Aristotle argues celestial bodies are spheres.

    Aristotle argues celestial bodies are spheres.
    Aristotle used a number of proofs that the Earth is a sphere, including the observation that its shadow on the Moon during lunar eclipses is always a circle
  • 500

    Xenophanes concludes that the Earth is very old.

    Xenophanes concludes that the Earth is very old.
    Xenophanes reasoned that stratified rocks were laid down as layers of sediments on the ocean floor. Given the thickness of the rocks, he concluded that the Earth is ancient.
  • 550

    Pythagoras and students develop model of solar system.

    Pythagoras and students develop model of solar system.
    Pythagoras and students develop model of solar system. The model of Pythagoras used circular paths for the celestial bodies and assumed most celestial bodies are spheres.

  • S. Chandrasekhar shows white dwarf stars are made of degenerate electrons.

    S. Chandrasekhar shows white dwarf stars are made of degenerate electrons.
    Chandrasekhar also showed that the more massive a white dwarf, the smaller it is and that there is a maximum mass, the Chandrasekhar limit, that a white dwarf can have.

  • Karl Jansky makes first radio astronomy observations.

    Karl Jansky makes first radio astronomy observations.
    Jansky found that the Milky Way galaxy is a source of radio emission

  • Grote Reber builds first radio telescope

    Grote Reber builds first radio telescope
    Reber built the first antenna specifically designed for radio astronomy. Using the radio telescope, Reber made the first map of cosmic radio emission.

  • Lin and Frank Shu explain spiral arms of Milky Way.

    Lin and Frank Shu explain spiral arms of Milky Way.
    Lin and Frank Shu explain spiral arms of Milky Way. Lin and Shu explained that the spiral arms are the crests of density waves that rotate through the galaxy

  • NASA

    NASA
    NASA received a double set-back when first the Mars Climate Orbiter and then the Mars Polar Lander space craft fail.

  • Sadbury reutrino detector

    Sadbury reutrino detector
    Sudbury neutrino detector in Canada demonstrates that neutrinos emitted from the Sun's core change their type as they travel to Earth. This resolves the many decade long mystery of the "missing solar neutrinos" and proves these tiny particles have mass.