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• Ptolemy (90 - 168 A.D.)

  • Greek astronomer, astrologer and geographer
  • Built the geocentric model with Earth at the centre and circular orbits
  • Geocentric model
  • 'Geo' means Earth
  • 'Centric' means centre
  • Earth is at the centre of the Solar System
  • Earth is stationary and all the objects such as the Sun and other planets revolve around Earth in circular orbits

  
• Copernicus (1473 - 1543)

  • Polish astronomer, mathematician, economist and doctor
  • Built the heliocentric model with the Sun at the centre and circular orbits
  • Heliocentric model
  • 'Helio' means the Sun
  • 'Centric' means centre
  • The Sun is at the centre of the Solar System
  • Earth rotates on its axis and revolves around the Sun in a circular orbit

  
• Kepler (1571 - 1 630)

  • German astronomer, mathematician and astrologer
  • Modified the heliocentric model with the Sun at one common focal point on the elliptical orbits of the planets according to Kepler's Law

  
• Astronomy

  • A science field that studies the universe as well as objects within it such as planets, moons, stars and galaxies
• 1. Greek astronomers are one of the earliest to study objects in outer space
  2. They claims that the Earth is spherical and have done several attempts to measure its size
• Islamic astronomy

  • Written in Arabic and are developed by scientists in the Middle East, North Africa, Spain and Central Asia
  • Influence -
  • Naming of several stars using Arabic language
  • Some terms also derived from Islamic astronomy
  • Trigonometirc, algebraic and algorithm principles are used in astronomical development
  • Astrolabes and observational labs help astronomers conduct research