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PHYSICS · Stage 7 · Chapter 5: The Earth in Space

Physics 5.6 Changing ideas 1: ancient astronomy

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Physics 5.6 Changing ideas 1: ancient astronomy — Alhussan International Academy — Physics (Stages 7–9) notes: Describe contributions of ancient astronomers from different cultures and explain how measurement and writing helped develop explanations.Ancient stories — People told s…

  • Scientific method
  • Prediction
  • Brahmagupta
  • Planet positions
  • Egyptian calendar
  • Nabta Playa

Section 1 of 5Stories and scientific explanations

1Ancient stories3 points
  • People told stories to explain events such as sunrise, sunset, eclipses and the seasons.
  • Many cultures told that the Sun was eaten by dragons, demons or gods during an eclipse.
  • Such stories were not based on evidence, so this is not what scientists do.
2Scientific method3 points
  • Scientists ask questions, collect evidence and develop explanations that account for the evidence.
  • Evidence comes from observations or measurements.
  • An explanation may use a model, which is a physical or mathematical way of explaining how something works.

Section 2 of 5Numbers and writing

  • Measurement
    • Numbers allowed people to measure the positions and movements of objects in the sky.
  • Writing
    • Recorded results made it possible to look for patterns over many years.
  • Prediction
    • Patterns in records allowed repeating events such as moon phases and eclipses to be predicted.

Section 3 of 5Astronomy in India

  • Aryabhata
    • Born in Bihar in 476, he explained the motion of the stars by the Earth spinning on its axis rather than the stars moving.
    • The Earth's spin also explained day and night.
    • His model predicted lunar and solar eclipses, replacing explanations based on dragons or demons.
  • Brahmagupta
    • He described a law of gravity about a thousand years before Newton.
  • Planet positions
    • Brahmagupta also worked out a method for calculating the positions of planets and when they rise and set.

Section 4 of 5Astronomy in Africa

1Egyptian calendar3 points
  • The Egyptians made a huge number of observations and worked out a calendar of 365 days.
  • The calendar records that the seasons change over a year.
  • It does not mean the Egyptians knew the Earth orbits the Sun in 365 days.
2Nabta Playa2 points
  • This site in southern Egypt is one of the oldest known astronomical sites.
  • More than 7000 years ago people placed stones that lined up with where certain stars would rise.
3West Africa2 points
  • People were probably measuring the stars many thousands of years ago.
  • At Namoratunga near Lake Turkana in Kenya, stones were placed and tilted in 300 BCE to make an astronomical calendar pointing to stars at particular times.

Section 5 of 5Babylonian and Islamic astronomy

  • Babylonia
    • In what is now Iraq, people made the earliest records of astronomical observations, giving planet positions and eclipse dates.
    • Greek and Indian astronomers later used these observations.
  • Ibn al-Haytham
    • Born in Basra in 956, he thought that the Earth was spinning on its axis.
  • Al-Biruni
    • Born in Uzbekistan about 1000 years ago, he developed a model to explain the phases of the Moon.
  • Observatories and instruments
    • Islamic science built many observatories and invented new instruments such as the astrolabe.
    • These instruments allowed very precise measurements of stars and planets.
    • Astronomers made detailed charts of the positions of the stars.

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