ancient civilizations believed that earth was th century b
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Ancient civilizations believed that Earth was at the center of the universe—GEOCENTRIC MODEL
Age of Reason beginning to recognize Sun is center of Solar System—HELIOCENTRIC MODEL
Age of Technology exploring wide reaches of the universe
5th century B.C. Moon is a sphere lighted
by Sun
•http://www-history.mcs.st-andrews.ac.uk/Biographies/Anaxagoras.html
4th century BC Earth is a sphere
•http://www.hao.ucar.edu/public/education/sp/images/aristotle.html
3rd century BC Mathemetician Placed Sun at center
with Earth orbiting itwith Earth orbiting it
•http://en.wikipedia.org/wiki/Eratosthenes#Measurement_of_the_Earth
2nd century AD Copies of works
survive to this dayT l t d t Translated to Arabic early, to Latin in 13th
century
•http://archive.ncsa.uiuc.edu/SDG/Experimental/vatican.exhibit/exhibit/full-images/d-mathematics/math21.gif
Mars usually moves across sky west to east Occasionally appears to move east to west Occurs when Earth is ‘passing’ Mars
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Thought Earth was the unmoving center
Translated into Latin in 13th century Influenced intellectual thought for centuries
Earth would fly apart if it rotated on an axis Moon would be left behind if Earth orbited Sun Since God created Earth and Sun and all the
heavenly bodies, Earth is the center of the heavenly bodies, Earth is the center of the universe
Earth rotates on an axis, instead of everything orbiting Earth
Earth orbits Sun like the planets, so it a planet too
“On the Revolution of the Heavenly Spheres”, 1543
http://www.hao.ucar.edu/public/education/sp/images/copernicus.html
Detailed observations of movement of planets
http://www.hao.ucar.edu/public/education/sp/images/tycho.html
His careful observations and records are his most important legacy
http://www.hao.ucar.edu/public/education/sp/images/tycho.3.html http://www.hao.ucar.edu/public/education/sp/images/tycho.1.html http://www.hao.ucar.edu/public/education/sp/images/tycho.2.html
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Discounted Copernicus model because he could not discern stellar parallax
It does exist, he didn’t have tools to see it
http://www.hao.ucar.edu/public/education/sp/images/tycho.4.html
Tycho’s assistant and successor
Used Tycho’s data to determine planetary determine planetary orbits are elliptical
http://en.wikipedia.org/wiki/Image:Johannes_Kepler.jpg
Orbit of planet is ellipse
Sun at one Focus
Equal areas in equal time intervals accounts for the uneven speeds
p2=d3
p=Period (time to orbit Sun) in Earth yearsd=Distance in Astronomical Units:
1 A.U.=distance from Earth to Sun
Strong supporter of Copernican model of planetary movement
Built 30x telescopes u lt 30 telescopes (from descriptions of the devices) and looked at planets and Moon starting in 1609
http://en.wikipedia.org/wiki/Galileo_Galilei#Technology
Telescope used to see that another body in solar system is a center of orbital movement
These moons are not left behind, and Earth’s Moon is not either
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When viewed by telescope, planets look like discs, not points of light as stars do
Jupiter has moons Venus has phases Venus has phases Moon’s surface has texture Sun rotates on an axis
Explained the orbital motion of planets as the interaction of inertia and gravity
Invented the calculus to simplify his calculations of motion
Sun is at the center of the solar system Published by Copernicus
Supported by Galileo’s telescopic observations of Jupiter and Venus
Kepler determined orbits are ellipses Newton determined orbits created by
interaction of inertia and gravity
1851 Supports that Earth does
rotate on its axis—Copernicus’ hypothesis