Astronomy Timeline
| c30,000 BC |  |
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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. P 24, F 2.20. |
| c4000 BC | |
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Mesopotamian ziggurats serve as observatories. Mesopotamian astronomers made careful observations from the tops of pyramid-like towers called ziggurats. P 32, F 3.1. |
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| c2500 BC | |
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Building of Stonehenge. The building of Stonehenge took place over many centuries. Alignments of the stones at Stonehenge mark the rising and setting points of the Sun at the solstices. P 20, F 2.14. | |
| c2000 BC | |
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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. P 21, F 2.16. | |
| c2000 BC | |
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Lunar eclipse observed at Ur in Mesopotamia. The oldest known recording of a lunar eclipse took place at Ur more than 4000 years ago. P 175. | |
| c1300 BC | |
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Chinese begin centuries long series of obs of eclipses. Chinese astronomers recorded 900 solar and 600 lunar eclipses over a period of 2600 years. P 46. | |
| c700 BC | |
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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. P 32 . | |
| c700 BC | |
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Hesiod describes practical uses for astronomy. Hesiod's poem The Works and Days contains practical astronomical advice for navigation and for agricultural activities. P 34. | |
| 585 BC | |
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Thales said to have predicted solar eclipse. The eclipse took place during a battle between the Lydians and the Persians. They were so stunned by the eclipse they ended the battle. P 34. | |
| c580 BC | |
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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. P 35. | |
| c560 BC | |
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Anaximenes proposes model of cosmos. In Anaximenes model the stars are fixed to the inside of a solid vault surrounding the Earth. Later Greek astronomers develop this idea into the concept of the celestial sphere. P 35. | |
| c550 BC | |
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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. P 35. F 3.5. | |
| c500 BC | |
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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. P 148. F 8.9. | |
| c450 BC | |
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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 148. | |
| 413 BC | |
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Lunar eclipse delays evacuation of Athenian army from Sicily. The Greeks regarded eclipses as uncertain omens. The delay doomed the Athenian army. P 176. | |
| c400 BC | |
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Eudoxus explains retrograde motion. Eudoxus's explanation involved the rotation of spheres in opposite directions. This geocentric model had the Earth at its center. P 36. F 3.6. | |
| c350 BC | |
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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. Pp 37-38. F 3.7, 3.8. | |
| c280 BC | |
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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. Pp 39-42. F 3.9, 3.11, 3.12, 3.13. | |
| c250 BC | |
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Eratosthenes finds circumference of Earth. Eratosthenes uses observations of the altitude of the Sun to find the circumference of the Earth. His estimate may have been accurate to within a few percent. Pp 42-43. F 3.14. | |
| 134 BC | |
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Hipparchus discovers precession, prepares stellar catalog. Hipparchus compared his own observations with earlier ones to discover precession, the slow change in the direction of the Earth's polar axis. He also made what was probably the first catalog of the positions and brightnesses of the stars. Pp 43-44. F 3.15, 3.16. | |
| c 0 AD | |
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Building of Bighorn Medicine Wheel. Plains Indians of North America built medicine wheels, monuments made of piles of stones. Alignments in the medicine wheels often pointed toward the direction of sunrise at the winter solstice. P 20. F 2.15. | |
| c140 | |
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Ptolemy "perfects" geocentric model of solar system. In Ptolemy's model the planets moved on circles (epicycles) that moved on other circles (deferents). The model could accurately predict the positions of the planets. Ptolemy also compiled a catalog of stellar brightnesses based partly on the earlier catalog of Hipparchus. Pp 44-46. F 3.17, 3.18, 3.19. | |
| 1054 | |
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Chinese record supernova that produces Crab Nebula. Chinese astronomers observed a supernova that was visible in the daytime. The matter blasted outward by the supernova later became observable as the Crab Nebula. Pp 459, 464. F 20.16 | |
| 1066 | |
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Comet Halley considered ill omen for King Harold. The appearance of Comet Halley in 1066 was considered an ill omen for Harold, King of England. Later that year Harold was killed in the Norman invasion of England. P 342. F 15.16, 15.17. | |
| c1200 | |
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Establishment of first universities in Europe. The development of astronomy was aided by the birth of universities at Bologna, Oxford, Paris, and a few other European cities. Pp 52-53. |
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