ancient..

• He also stated that the celestial motion was circular or spherical, uniform, and constantly regular.

  plato
• He was unable to explain the imperfect motions of the sun, moon, and planets or also known as the Retrograde motion.

  plato
• Retrograde Motion - refers to the apparent change in the movement of the planet through the sky.
• First astronomer to present a geocentric model of the

  universe

  Eudoxus of Cnidus (390 – 337 BCE)
• His model also claimed that the universe was composed of five other planets aside from the Earth namely: Mercury, Venus, Mars, Jupiter, and Saturn.

  Eudoxus of Cnidus
• believed that space is fundamentally different from the Earth.

  Aristotle
• He was the first to conceive the idea that the Sun, not the Earth was the center of the universe.

  Aristarchus of Samos (310 –230 BCE)
• He first suggested that the Earth rotates on its own axis

  Aristarchus of Samos (310 –230 BCE)
• He knew that the planets don’t appear to orbit in perfect circles around the Earth.

  ptolemy
• His claimed that:- Earth is spherical object that is freely suspended at the center of the universe.- The stars are fixed bodies attached to a solid sphere exterior part of the universe.

  ptolemy
• Ptolemaic Model of Universe • Some planets, like Mars, even appear to move backwards before moving forwards again in large loops. • Ptolemy suggested that planets like Mars move in circles as they orbit the Earth, where the circles are called epicycles, which also move around the Earth on a larger circular path called deferent.
• He proposed the geo-heliocentric universe model.

  tycho brahe
• ✔He discovered a supernova in the constellation of Cassiopeia in 1572

  tychi brahe
• ✔He made careful observations of a comet in 1577 and showed that the comet was further away from the Earth that the moon from the Earth.

  tycho brahe
• He built his own comprehensive astronomical telescopeto explore the heavens.

  galileo galilei