Gravity and motion
Download
1 / 25

Gravity and Motion - PowerPoint PPT Presentation


  • 332 Views
  • Updated On :

Gravity and Motion. The Early History of Astronomy. Topics. Introduction Geocentric Astronomy Summary. Introduction. Geocentric Astronomy. 4000 BC – 700 AD. Origins of Astronomy. 4000 – 500 BC Chaldean, Babylonian, Egyptian, Chinese, Indian, ... Grouped stars into constellations.

loader
I am the owner, or an agent authorized to act on behalf of the owner, of the copyrighted work described.
capcha
Download Presentation

PowerPoint Slideshow about 'Gravity and Motion' - mike_john


An Image/Link below is provided (as is) to download presentation

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.


- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -
Presentation Transcript
Gravity and motion l.jpg

Gravity and Motion

The Early History of Astronomy


Topics l.jpg
Topics

  • Introduction

  • Geocentric Astronomy

  • Summary



Geocentric astronomy l.jpg

Geocentric Astronomy

4000 BC – 700 AD


Origins of astronomy l.jpg
Origins of Astronomy

  • 4000 – 500 BC Chaldean, Babylonian, Egyptian, Chinese, Indian, ...

    • Grouped stars into constellations.

    • Babylonians divided circumference into 360 degrees; 1 degree into 60 minutes; 1 minute into 60 seconds.

    • Believed stars controlled human destiny.


Ancient greece l.jpg
Ancient Greece

http://plato-dialogues.org/tools/gk_wrld.htm


Greek astronomy l.jpg
Greek Astronomy

  • 624 - 548 BC Thales

    • Founded Ionian School of Philosophers.

    • Declared universe is understandable in terms of simple rules.

    • Rejected superstition.

    • Earth floats in a vast ocean.  

  • 610 - 547 BC Anaximander

    • Earth isolated, and unsupported, in space.


Greek astronomy ii l.jpg
Greek Astronomy – II

  • 560 – 480 BC Pythagoras of Samos

    • Discovered relationship between rational numbers and musical intervals. 

    • The goal of the Philosophos, the Lover of Wisdom, was to discover rules of Nature through deep reflection.  

    • Decided upon spiritual grounds that the Earth was spherical – the perfect shape.


Greek astronomy iii l.jpg
Greek Astronomy – III

  • 428 – 348 BC Plato

    • Space is infinite and contains a finite, spherical, universe at the center of which lies the Earth.

    • The visible world is but a distorted copy of the real world of Ideas. Pythagorean program abandoned.

    • The shape of the Earth must be a sphere and all heavenly motion must be circular.


Greek astronomy iv l.jpg
Greek Astronomy – IV

  • 384 - 322 BC Aristotle

    • Joined Plato's Academy in 367 BC.

    • Tutored young prince who would become Alexander the Great, the founder of the city of Alexandria in 332 BC.

    • Like Pythagoras, Aristotle believed that mathematics was the key to a true understanding of Nature.

    • Promoted idea of circular motion into a dogma of astronomy along with geocentrism.


Greek astronomy v l.jpg
Greek Astronomy – V

  • 310 BC Aristarchus of Samos

    • Last of the great Pythagoreans.

    • Developed a heliocentric model.

    • Alas his ideas all but died with him.

    • This model re-discovered by Copernicus 17 centuries later.


Greek astronomy vi l.jpg
Greek Astronomy – VI

  • 276 - 194 BC Eratosthenes of Alexandria

    • Determined circumference of the Earth. 

    • At the Summer Solstice the Sun is vertical at Syene but at Alexandria it is 7.25 degreessouth of the vertical. 

N

S

Alexandria

Syene



The circumference of the earth l.jpg
The Circumference of the Earth

Sunlight

Shadow

A

Alexandria

C / D = 360 / A

C = D * 360 / A

= 500*360 / 7.5

= 24,000 miles

D

Syene

A = 7.5o

D = 500 miles

C = Circumference

A

Center of the Earth


End of greek astronomy l.jpg
End of Greek Astronomy

  • 190 – 120 BC Hipparchus

    • The greatest astronomer of antiquity.

    • From his precise observations he became convinced that Aristotle was wrong about circular motion.

    • Created a more accurate model of planetary motion in which he introduced epicyclesinto the geocentric model.

    • Became the accepted model of the universe for the next 1600 years!


The empire of rome l.jpg
The Empire of Rome

  • 47 BC – 30 AD Roman Empire at its height

    • Era of Cleopatra, Julius Caesar and Mark Anthony.

    • Era of Jesus of Nazareth.

    • Roman conquest of the Middle East.

  • 100 - 170 AD Claudius Ptolemeus (Ptolemy)

    • Wrote great textbook: The Almagest summarizing Greek astronomy and his own astronomical theories.


Planets the vagabond stars l.jpg
Planets: The Vagabond Stars

Retrograde Motion

Prograde Motion



Descent into darkness l.jpg
Descent into Darkness

  • 642 AD Fall of Alexandria

    • After a 14-month siege by Arabian troops, Alexandria was all but destroyed.

    • The great library was razed to the ground. 

  • Dark Ages (700 AD – 1400 AD)

    • The West enters a period of stagnation.

    • Greek astronomy passed on to the Arabs, via India. This knowledge is preserved and extended by Islamic scholars in Baghdad. 


The dark ages l.jpg
The Dark Ages

  • Period of Western history characterized by

  • terror and despair, in populations oppressed, famished, and wretched to a degree almost unimaginable today. To the miseries of constant war, political and social disintegration, there was added the dreadful affliction of inescapable, mysterious, and deadly disease. Mankind stood helpless as though trapped in a world of terror and peril against which there was no defense.

  • The Sleepwalkers by Arthur Koestler


  • The great re awakening l.jpg
    The Great Re-Awakening

    • 760 AD

      • Islamic leaders in Baghdad sponsored translations of old Greek texts. 

    • 1000 AD

      • The Islamic empire spreads to Spain.

      • Greek-Arabian science enters the West.

    • 1400 AD

      • Gradually, the West awakens from its long dark sleep. 


    Summary l.jpg
    Summary

    • 4000 BC ~ 500 BC

      • The earliest ideas about astronomy grew from astrology, the superstitious belief in the influence of stars on human affairs.

    • 600 BC ~ 100 BC

      • Abandonment of superstition and embrace of reason. Golden age of ancient Greece

    • 100 BC ~ 200 AD

      • Consolidation of ancient Greek astronomy


    ad