astronomy time line

By Harlin Debien
  • 30,000 BCE

    Earliest known recording of the skies

    Earliest known recording of the skies
    Bone carvings keep track of phases of Moon. Early people engraved patterns of lines on animal bones to keep track of the phases of the Moon.
  • 4000 BCE

    First observatories

    First 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
    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
  • 700 BCE

    Babylonians predict lunar eclipses

    Babylonians predict lunar eclipses
    The Babylonians used their long record of eclipses to see regular patterns of eclipses. They used these patterns to predict lunar eclipses.
  • 700 BCE

    Hesiod describes practical uses for astronomy

    Hesiod describes practical uses for astronomy
    Hesiod's poem The Works and Days contains practical astronomical advice for navigation and for agricultural activities.
  • 580 BCE

    Anaximander describes model of Earth

    Anaximander describes model of Earth
    Sun, Moon, stars. Anaximander's model was the forerunner of later Greek attempts to explain the heavens in non-mythological terms.
  • 550 BCE

    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.
  • 450 BCE

    Herodotus concludes Earth is at least thousands of years old

    Herodotus concludes Earth is at least thousands of years old
    Herodotus reasoned that it would have taken millenia for the annual Nile flood to have produced the Nile delta. p.160.
  • 400 BCE

    Eudoxus explains retrograde motion

    Eudoxus explains retrograde motion
    Eudoxus explains retrograde motion. Eudoxus's explanation involved the rotation of spheres in opposite directions. This geocentric model had the Earth at its center
  • 350 BCE

    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.
  • 280 BCE

    Aristarchus finds relative dimensions of solar system

    Aristarchus finds relative dimensions of solar system
    Aristarchus concluded that the Earth was much smaller than the distances to the celestial bodies. He also invented a heliocentric (Sun-centered) model for the solar system.