history of astronomy. early astronomy astronomy is science that the universe greeks 600 b.c. –...
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History of Astronomy
Early Astronomy
Astronomy• Is science that the universe Greeks• 600 B.C. – A.D. 150• Measured distances to the Sun and Moon
Eratosthenes
EratosthenesSuccessfully Measured
the circumference of the Earth
1.7% Error 2400 Years Ago
Geocentric View
Geocentric View Pre 300 B.C.Earth is the center of
the UnivereseThe orbs (Sun, Moon,
Mercury, Venus, Mars and Jupiter) orbit the Earth each day
Surrounded by a Hollow Sphere
Heliocentric
Aristarchus (312-230 B.C.)• Earth and the other
planets orbit the sun• Dominated Western
Thought for over 2000 Years
Ptolemaic System
Ptolemy (A.D. 141)• Believed in Geocentric
Model• Observed Retrograde
Motion– Planets Move to the
East, but periodically they stop and reverse direction
• Social Bias in Science
Modern Astronomy
Renaissance of Science• Broke Away from Religious and Philosophical
Views• Used Natural Laws to explain the motions of
the Heavens
Modern Astronomy
Nicolas Copernicus• 1473-1543• Earth is a Planet• Sun Centered• Planets Orbited the Sun
in Complete Circles
Modern Astronomy
Tycho Brahe• 1546 -1601• Spent 20 yrs. Measuring
the Locations of the Heavenly Bodies
Johannes Kepler• 1571-1630• Assistant to Brahe• Discovered 3 Laws of
Planetary Motion– Ellipse
• Determined the Distance from the Sun to Earth is 1AU = 150 Million km
Modern Astronomy
Galileo Galilei• 1564 – 1642• Major Contribution was
the behavior of the Moving Objects
• Ground Lenses to make telescopes
• Made Discoveries that supported Heliocentric View
Sir Isaac Newton• 1642-1727• Expanded on Galileo
Force• Formulated and tested
the Law of Universal Gravitation at the age of 23
• This is the force that makes planets revolve in a circle