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Celestial Mechanics. Cosmogony: model of our place in the Universe. Celestial Mechanics. Definition:. is the branch of astronomy that deals with the motions of celestial objects. Ancient to Modern Astronomy. Most of the reading you will be receiving will come from this website.
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Celestial Mechanics Cosmogony: model of our place in the Universe
Celestial Mechanics Definition: is the branch of astronomy that deals with the motions of celestial objects.
Ancient to Modern Astronomy Most of the reading you will be receiving will come from this website. http://csep10.phys.utk.edu/astr161/lect/index.html
Wandering Stars Website with Wandering Stars and Retrograde motion animation: • http://www.keplersdiscovery.com/Intro.html
Celestial Sphere – A model • Imaginary sphere around the Earth in which stars in space appear – It is not physical as the ancients believed! • Represents only the stars we can see with our eyes. And the are fixed (So no, planets, exoplanets, pulsars, other stars we can’t see, etc…) • Earth centered
Aristotle’s Universe • Earth centered • 55 concentric crystalline spheres • Buffering spheres in between • Attached to one main sphere - Controlled by the Prime Mover • Each sphere rotated at a different rate • Orbits were in Uniform circular motion
Beliefs of Aristotle and Ptolemy • All motion in the heavens is uniform circular motion. • The objects in the heavens are made from perfect material, and cannot change their intrinsic properties (e.g., their brightness). • The Earth is at the center of the Universe.
Apparent Motion of Planets on the Celestial Sphere Reading and Applet: • http://csep10.phys.utk.edu/astr161/lect/retrograde/retrograde.html
Retrograde Motion Varying brightness of the planets Observation Issues Starry Night Pro Simulation http://www.youtube.com/watch?v=cSU5VwIQTNI&feature=related
Retrograde Motion http://www.mhhe.com/physsci/astronomy/applets/Retro/frame.html Handout: Retrograde motion (this handout is not available as digital copy. Please see Mrs. Carter for this handout) Another good retrograde motion simulator: http://astro.unl.edu/classaction/loader.html?filename=animations/renaissance/retrograde.swf&movieid=retrograde&width=700&height=600&version=6.0.0
Geocentric Models: Aristotle and Ptolemy Aristotle: Epicycle Ptolemy: Epicycle upon Epicycles http://csep10.phys.utk.edu/astr161/lect/retrograde/aristotle.html http://www.polaris.iastate.edu/EveningStar/Unit2/unit2_sub1.htm
Ptolemy’s model of the orbit of Mars http://astro.unl.edu/classaction/loader.html?filename=animations/renaissance/marsorbit.swf&movieid=marsorbit&width=825&height=550&version=6.0.0
Motions of Mercury and Venus Observations Mercury and Venus were always close to the Sun Conclusions The Spheres of Mercury, Venus and the Sun must be connected. SUNRISE
Development of Modern Astronomy Copernicus Kepler Brahe Galileo Newton Einstein
Ancient Astronomy From Ancient to Modern (Up to Newton) http://www.youtube.com/watch?v=fMepqsms-bk Another video The Universe: Aristotle and Ptolemy Video http://www.youtube.com/watch?v=wGZdaOsuodQ&feature=relmfu
The Copernican model: A Sun-Centered Universe (1543) Copernican Heliocentric Universe New views of the heavens Sun Centered Stars do NOT revolve around the Earth Earth rotates in 24 hours But… Planets still have perfectly circular orbits and EPICYCLES ARE STILL NEEDED Retrograde motion and the varying brightness of planets in the Heliocentric Model: http://csep10.phys.utk.edu/astr161/lect/retrograde/copernican.html http://www.history.com/shows/the-universe/videos/playlists/beyond-the-big-bang#beyond-the-big-bang-copernicus
Copernicus determines Mars is beyond our orbit What time is it in this picture? Link to me: • Sun rise – 6:20 am • Sun set – 5:55 pm Length of Day ~ 11.5 hours When is the middle of the night?
Aristotle's Common Sense Let’s see how much common sense you have: • Why don’t objects fly off the Earth as the Earth spins? • Why don’t we leave behind the birds, airplanes and satellites that are in the air as we orbit around the sun? • Why don’t we notice an apparent shift in position of the stars as we move around the sun?
TRY THIS • Close one eye • Line your index finger up with this rectangle • Now switch eyes • Is your finger still lined up with the rectangle. • Switch back and forth between eyes. • Observe the apparent change in position of your finger. How does changing the distance your finger is from your eye affect the apparent shift in your fingers position?
Parallax Basic Concept Comparison of Large and Small Angles Stellar Parallax simulation: http://highered.mcgraw-hill.com/olcweb/cgi/pluginpop.cgi?it=swf::800::600::/sites/dl/free/007299181x/78778/Parallax_Nav.swf::Stellar%20Parallax%20Interactive
Aristarchus of Samos (310BC - 230BC) Link to the image to learn more about Aristarchus of Samos and his theory behind why the moon orbited the earth and the earth orbited the Sun.
Tycho Brahe (1546 - 1601) These instruments were able to measure parallax Danish Astronomer Instruments
Observations of TychoBrahe Reading: http://csep10.phys.utk.edu/astr161/lect/history/brahe.html Precise observations of Mars’s position
Supernova 1572 NO OBSERVED PARALLAX – MUST NOT BE CLOSE BY!(This was something that changed!) Could not measure parallax for the stars!
Tychonic Geo-Heliocentric Model Characteristics • The Moon and Sun orbited the Earth • The other planets orbited the SunLink to animationhttp://www.keplersdiscovery.com/Hypotheses.html
Drama Time It’s been said that maybe Kepler killed Brahe. Use the internet to research Johannes Kepler and Tycho Brahe to see what you can find about this rumor. Why hasn’t Hollywood made this movie yet!! Total Drama.
Kepler’s 3 Laws of Planetary Motion LAW 1: ALL PLANETS ORBITS ARE ELLIPSES Reading: http://csep10.phys.utk.edu/astr161/lect/history/kepler.html Applet http://solarsystem.colorado.edu/home/highRes.html
Ellipses http://www.keplersdiscovery.com/Elipse.html One focus is the sun Aphelion – furthest point from the sun Perihelion – nearest point to the sun Major axis – long axis Minor axis – short axis
Eccentricities: Bound & Unbound Orbits Describe how e changes as the focal distances axis increases. Describe how e changes as the focal distance decreases. Calculate the eccentricity of a Line Circle
Kepler’s Second Law of Planetary motion Equal Areas in equal Times
Kepler's Laws Animations Link with excellent animations: http://www.keplersdiscovery.com/AreaTime.html Handout: Kepler's 2nd and 3rd Laws Review: http://schools.wikia.com/wiki/Newton's_Law_of_Universal_Gravitation#Kepler.27s_First_Law:_on_Orbits
Kepler’s 3rd Law of Planetary Motion
Distances in the Solar System The Astronomical Unit
The IAU and astronomical units Read this article about the AU • http://www.iau.org/public/measuring/
Using the AU Calculating distances to the planets in Astronomical Units
Galileo and the telescope Reading http://csep10.phys.utk.edu/astr161/lect/history/galileo.html http://csep10.phys.utk.edu/astr161/lect/history/aristotle_dynamics.html Web link to Galileo Videos • http://www.history.com/shows/the-universe/videos/playlists/beyond-the-big-bang#beyond-the-big-bang-galileo-galilei
Galileo’s idea of Inertia • Inertia: tendency of an object to resist changes in its velocity • Velocity is the change in an objects motion (either speed or direction)
Galileo’s idea on Falling Objects Galileo’s Experiment Reenactment • replace Galileo’s Experiment on the Moon http://www.youtube.com/watch?v=L55jImEhNZ0
Galileo's Observations Galileo used a telescope to make observations of objects that were too far or dim to see with the unaided eye.
One of the Greatest Religious Debates in HistoryGalileo and the Church • http://www.youtube.com/watch?v=NAra0BVjJp4&feature=related • http://www.youtube.com/watch?v=P3X_OZq7f70&feature=relmfu • http://www.youtube.com/watch?v=RsqHCnLMz_A&feature=relmfu • http://www.youtube.com/watch?v=ebZxMjvAu8Y&feature=relmfu
These observations include:http://www.bbc.co.uk/science/space/solarsystem/scientists/galileo_galilei An imperfect Moon Moon through a Telescope like Galileo’s http://www.youtube.com/watch?v=8bPUvsgCEnU Moon Dance Video http://www.astro.washington.edu/IYA/lunar_librations.html
Galileo's Observations Phases of Venus