Slide 1

History of Astronomy

Slide 2

Stonehenge Dates from Stone Age (2800 B.C.) Construction spanned 17 centuries

Slide 3

Sun Dagger Chaco Canyon, NM Sliver of light passes through carved stone at noon on the summer solstice

Slide 4

Ancient Chinese Observed the heavens, records of comets Historical data still used today

Slide 5

Muslim astronomy Key link from ancient Greeks during Dark Ages Examples of Muslim terms: Zenith and star names such as Vega, Betelgeuse

Slide 6

Ancient Greek Astronomy

Slide 7

Ionia the birthplace of science

Slide 8

Greek Models of the Universe Geocentric (Earth Centered) or Ptolemaic, A.D. 140

Slide 9

Ptolemaic model http://www.csit.fsu.edu/%7Edduke/nmoon6.html

Slide 10

Retrograde Motion of Mars

Slide 11

Jupiter and Saturn Retrograde motion http://antwrp.gsfc.nasa.gov/apod/ap011220.html

Slide 12

Heliocentric Model (Sun centered) Aristarchus (290 B. C.), forgotten for 1800 years

Slide 13

Nicolaus Copernicus Rediscovered Aristarchuss heliocentric model

Slide 14

De revolutionibus orbium coelestium De revolutionibus orbium coelestium (On the Revolutions of the Celestial Spheres) Published just before his death in 1543 Starting point of modern astronomy Placed on the Catholic Churchs Index of Prohibited Books in 1616

Slide 15

Galileo Galilei Built a telescope in 1609 His work supported Copernicus Found 4 moons orbiting Jupiter

Slide 16

Published Sidereus Nuncius (The Starry Messenger) in 1610 Banned in 1616

Slide 17

Johannes Kepler Contemporary of Galileo

Slide 18

Keplers First Law The orbital paths of the planets are elliptical, not circular, with the Sun at one focus

Slide 19

Keplers 1 st Law

Slide 20

Keplers Second Law An imaginary line connecting the Sun to any planet sweeps out equal areas of the ellipse in equal intervals of time

Slide 21

Keplers second law http://www.youtube.com/watch?v=_3OOK8a 4l8Y&feature=related http://www.youtube.com/watch?v=_3OOK8a 4l8Y&feature=related http://www.astro.virginia.edu/class/oconnell/ astr121/im/kepler-2ndanim-NS.gif http://www.astro.virginia.edu/class/oconnell/ astr121/im/kepler-2ndanim-NS.gif

Slide 22

Keplers Third Law The square of a planets orbital period is proportional to the cube of its semimajor axis P 2 = a 3 where P is in Earth years and a is in astronomical units 1 astronomical unit (AU) = avg. distance from the Earth to the Sun

Slide 23

Slide 24

Plutos semimajor axis (average distance from the Sun) is approximately 40. AU. Calculate the period of Pluto a = 40. AU And a 3 = 64,000 P 2 = a 3 P 2 = 64,000 P = 64,000 P = 250 years

Slide 25

Issac Newton Published Philosophiae Naturalis Principia Mathematica in 1687 Possibly most influential physics book ever written Newtonian mechanics WHY the planets move according to Keplers Laws

Slide 26

Newtons inverse square law The acceleration due to gravity is inversely proportional to the square of the distance

Slide 27

Newtons Cannon http://galileoandeinstein.physics.virginia.edu/ more_stuff/Applets/newt/newtmtn.html http://galileoandeinstein.physics.virginia.edu/ more_stuff/Applets/newt/newtmtn.html

Slide 28