cosmogony: model of our place in the universe
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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. - PowerPoint PPT PresentationTRANSCRIPT
Cosmogony: model of our place in the
Universe
Celestial Mechanics
Celestial MechanicsDefinition:
is the branch of astronomy
that deals with the motions of
celestial objects.
Most of the reading you will be receiving will come from this website.
http://csep10.phys.utk.edu/astr161/lect/index.html
Ancient to Modern Astronomy
Wandering Stars
Website with Wandering Stars and Retrograde motion animation:• http://www.keplersdiscovery.com/Intro.html
1. Imaginary sphere around the Earth in which stars in space appear – It is not physical as the ancients believed!
2. 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…)
3. Earth centered
Celestial Sphere – A model
• 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
Aristotle’s Universe
Beliefs of Aristotle and Ptolemy
1. All motion in the heavens is uniform circular motion.
2. The objects in the heavens are made from perfect material, and cannot change their intrinsic properties (e.g., their brightness).
3. 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
Observation Issues
Starry Night Pro Simulationhttp://www.youtube.com/watch?v=cSU5VwIQTNI&feature=related
1. Retrograde Motion2. Varying brightness of the planets
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 VenusObservations• Mercury and Venus were
always close to the SunConclusions• 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 Videohttp://www.youtube.com/watch?v=wGZdaOsuodQ&feature=relmfu
The Copernican model: A Sun-Centered Universe (1543)
Copernican Heliocentric Universe
http://www.history.com/shows/the-universe/videos/playlists/beyond-the-big-bang#beyond-the-big-bang-copernicus
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
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 pmLength of Day ~ 11.5 hoursWhen is the middle of the night?
Aristotle's Common Sense
Let’s see how much common sense you have:1. Why don’t objects fly off the Earth as the Earth
spins?2. Why don’t we leave behind the birds, airplanes
and satellites that are in the air as we orbit around the sun?
3. Why don’t we notice an apparent shift in position of the stars as we move around the sun?
TRY THIS1. Close one eye2. Line your index finger up with this
rectangle3. Now switch eyes4. Is your finger still lined up with the
rectangle.5. Switch back and forth between eyes.6. 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?
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
Parallax
Observed Parallax
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)
Danish AstronomerInstruments
These instruments were able to measure parallax
Observations of Tycho Brahe
Reading:http://csep10.phys.utk.edu/astr161/lect/history/brahe.html
Precise observations of Mars’s position
NO OBSERVED PARALLAX – MUST NOT BE CLOSE BY!
(This was something that changed!)
Could not measure parallax for the stars!
Supernova 1572
Tychonic Geo-Heliocentric Model
Characteristics• The Moon and Sun
orbited the Earth
• The other planets orbited the Sun
Link 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.
All orbits are slightly eccentric
All Planet Orbits
The Earth is not always the same distance from the Sun
Kepler’s 3 Laws of Planetary Motion
LAW 1: ALL PLANETS ORBITS
ARE ELLIPSES
Reading: http://csep10.phys.utk.edu/astr161/lect/history/kepler.htmlApplethttp://solarsystem.colorado.edu/home/highRes.html
Ellipses
One focus is the sunAphelion – furthest point from the sunPerihelion – nearest point to the sunMajor axis – long axisMinor axis – short axis
http://www.keplersdiscovery.com/Elipse.html
Eccentricities
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
Planet Eccentricities
Equal Areas in equal Times
Kepler’s Second Law of Planetary motion
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
Read this article about the AU• http://www.iau.org/public/measuring/
The IAU and astronomical units
Using the AU
Calculating distances to the planets in Astronomical Units
Galileo and the telescopeReading
http://csep10.phys.utk.edu/astr161/lect/history/galileo.htmlhttp://csep10.phys.utk.edu/astr161/lect/history/aristotle_dynamics.html
Web link to Galileo Videos 1. http://
www.history.com/shows/the-universe/videos/playlists/beyond-the-big-bang#beyond-the-big-bang-galileo-galilei
Galileo’s idea of Inertia
1. Inertia: tendency of an object to resist changes in its velocity
2. 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 Moonhttp://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 History
Galileo and the Church1. http://
www.youtube.com/watch?v=NAra0BVjJp4&feature=related 2. http://
www.youtube.com/watch?v=P3X_OZq7f70&feature=relmfu3. http://
www.youtube.com/watch?v=RsqHCnLMz_A&feature=relmfu 4. 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 Videohttp://www.astro.washington.edu/IYA/lunar_librations.html
Galileo's ObservationsPhases of Venus
Phases of Venus
According to the Geocentric Modelhttp://astro.unl.edu/classaction/loader.html?filename=animations/renaissance/ptolemaic.swf&movieid=ptolemaic&width=900&height=660&version=6.0.0
According to the Heliocentric modelhttp://astro.unl.edu/classaction/loader.html?filename=animations/renaissance/venusphases.swf&movieid=venusphases&width=870&height=600&version=6.0.0
Galileo's Observations
Moons around Jupiterhttp://www.youtube.com/watch?v=SsWMaAF0kmU
Galileo’s Observations
Ears on Saturn(it’s rings)
http://www.redorbit.com/news/video/space_2/2585749/are_saturns_rings_disappearing/
FUN FRIDAY
Carl Sagan on the history of Astronomyhttp://www.youtube.com/watch?v=IEhDkKfkWoI&feature=fvsr
Carl Sagan: COSMOS