What the ancient civilizations achieved
Determining the time of day, marking the seasons, lunar calendars, ancient structures and archaeosastronomy, navigation
First two established regions of civilization
Egypt and Mesopotamia
Modern science traces its roots to the
GREEKS who first created models and never referred to supernatural reasons
How did the Greeks explain planetary motion?
Geocentric model-earth at center
Came up with celestrial sphere
Anaxi Mander
Who had mystical interest in mathematical perfection?
Pythagoreans
Philipsphy that heavenly objects moved in perfect circles in constant speeds circling earth
Plato
Oppostion to Plato's philosophy
Greeks realized retrograde motion presented a problem
(1)Gravity pulled heavy things toward center, not light things, they float toward heavens- (2) Geocentric model (3) nested spheres model
Aristotle
Epicycle
little circles- retrograde motion
Deferent
big circles-retrograde motion
Hipparchus
developed circle upon circle idea but added another set of micro circles.
adapted ideas into single system, still problem with 1 archminute off
Ptolemy great accomplishments
(1) Alex the Great expanded empires of Egypt and Messopotamia, tutored by Aristotle. - Alexandria library was created around 330 BC - library destructed- held 1/2 million scrolls that were burned (2) Islamic (Iraq today) preservation of science (3) Scient
How was Greek knowledge preserved?
Who overturned Plotemac model?
Copernicas- Copernican Revolution
Copernicus started b/c of retrograde- used simple geometric equations- hesitated publishing works-published day he died-few converts b/c did not work well- believed in perfect circles- no more accurate than Plotemac model- created suncentered model
How did Copernicus challenge Earth-centered model?
Allignment of Jupitar and Saturn was two days later than Copernicus predicted-nova was farther away than moon- his data was the best naked eye observations- earth at center but planets orbit sun-provided data needed to improve suncentered model
How did Tycho challenge Earth- centered model?
Hired by Tycho- found circular orbits that matched Tycho's by 2 archminutes- wanted unified model and found that Tycho was off by 8 archminutes- Planetary orbits are ellipses, not perfect circles- made model that fit Tycho's data
How did Kepler challenge Earth- centered model?
Eccentricity
How much an ellispse deviates from a perfect circle
Major Axis
Long side of ellipse
Minor Axis
Short part of ellipse
Semi Major Axis
Half of major axis
Kepler's First Law
orbit of planets are ellipses with sun at one foci
Kepler's Second Law
Equal areas at equal times- plantes move faster when closer to the sun-
Kepler's Third Law
More distant planets orbit sun at slower avg speeds. p2=a3 P=orbital period A=avg. dist.
Perihelion
When planet is closest to sun in orbit
Aphelion
When planet is at furthest dist from sun
Length of Semimajor Axis?
avg. of perihelion and aphelion distances
3 Objections to Aristotle?
3 Objections- (1) Aristotle held that earth couldnt be moving (2) non-circular orbits contridicted Aristotle's claims that heavens are perfect (3) geocentric model would mean we should see stellar parallax
(1) moving balls, so objects stay in motion (2) took down heavenly perfection with telescope (3) stars are very far away (4) nail in coffin-- four moons orbiting Jupitar
How did Galielo solidify Copernicun Revolution?
Galielo
Book banned- recant claim-
Science Hallmarks
(1)Seeks explanation for observations, nothing divine or Biblical (2) Progresses thru creation and testing of models that explain observations (3) testable predictions that agree with observations
Scientific Meathod
observation, ask question, hypothisis, predict, test
Astronomy vs. Astrology
Astronomy- science focused on learning about how stuff works Astrology- search for hidden influenced on human lives based on planets and stars.
Metonic cycle
19 years, used to sychronize lunar and solar calendars
ptolemy did what for astronomy?
Geocentric model, accurate predictions of planatery motions
Galileo did not observe...
Stellar paralax
noon at the summer solitce
The sun dagger in new mexico pierces a spiral at....
Muslim fast of Ramadan occurs
during the ninth month of a 12-month lunar cycle
Mayans
Ancient culture that had the greatest known success in predicting eclipses
modern science emerged from ancient civilizations in which part of the world
the mediterranean and middle east