Transcript Ancient to Modern Astronomy

Cosmogony:
model of our
place in the
Universe
Definition:
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
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
• 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
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/retro
grade/retrograde.html
Observation Issues
1. Retrograde Motion
2. Varying brightness of the planets
Starry Night Pro Simulation
http://www.youtube.com/watch?v=cSU5VwIQTNI&feature=related
Retrograde Motion
http://www.mhhe.com/physsci/astronomy/appl
ets/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/r
etrograde.swf&movieid=retrograde&width=700&height=600&version=6.0.0
Geocentric Models:
Aristotle and Ptolemy
Aristotle: Epicycle
http://www.polaris.iastate.edu/E
veningStar/Unit2/unit2_sub1.ht
m
Ptolemy: Epicycle upon Epicycles
http://csep10.phys.utk.edu/astr161/lect/
retrograde/aristotle.html
Ptolemy’s model of the orbit of Mars
http://astro.unl.edu/classaction/loader.html?file
name=animations/renaissance/marsorbit.swf&
movieid=marsorbit&width=825&height=550&ve
rsion=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=fMepqsmsbk
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)
New views of the heavens
Copernican Heliocentric Universe
•
•
•
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
http://www.history.com/shows/theuniverse/videos/playlists/beyond-the-bigbang#beyond-the-big-bang-copernicus
Retrograde motion and the varying
brightness of planets in the
Heliocentric Model:
http://csep10.phys.utk.edu/astr161/le
ct/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 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:
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 THIS
1. Close one eye
2. Line your index finger up with this
rectangle
3. Now switch eyes
4. 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.mcgrawhill.com/olcweb/cgi/pluginpop.cgi?it=swf::800:
:600::/sites/dl/free/007299181x/78778/Paralla
x_Nav.swf::Stellar%20Parallax%20Interactive
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 Astronomer
These instruments were able to measure parallax
Instruments
Observations of Tycho Brahe
Precise observations of Mars’s position
Reading:
http://csep10.phys.utk.edu/astr161/l
ect/history/brahe.html
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 Sun
Link to animation
http://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.html
Applet
http://solarsystem.colorado.edu/home/highRes.html
http://www.keplersdiscov
ery.com/Elipse.html
Ellipses
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
Eccentricities: Bound & Unbound Orbits
𝑓𝑜𝑐𝑎𝑙 𝑑𝑖𝑠𝑡𝑎𝑛𝑐𝑒
𝑒=
𝑚𝑎𝑗𝑜𝑟 𝑎𝑥𝑖𝑠
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 Laws Animations
Link with excellent animations:
http://www.keplersdiscovery.com/AreaTime.ht
ml
Handout: Kepler's 2nd and 3rd Laws
Review:
http://schools.wikia.com/wiki/Newton's_Law_of_Universal_Gravitation#Kepler.27s_First_Law:_o
n_Orbits
Distances in the Solar System
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_dyn
amics.html
Web link to Galileo Videos
1. http://www.history.com/shows/theuniverse/videos/playlists/beyond-the-big-bang#beyondthe-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 Moon
http://www.youtube.com/watch?v=L55jImEhNZ
0
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 Church
1. http://www.youtube.com/watch?v=NAra0BV
jJp4&feature=related
2. http://www.youtube.com/watch?v=P3X_OZq
7f70&feature=relmfu
3. http://www.youtube.com/watch?v=RsqHCnL
Mz_A&feature=relmfu
4. http://www.youtube.com/watch?v=ebZxMjv
Au8Y&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_librat
ions.html
Galileo's Observations
Phases of Venus
Phases of Venus
According to the Geocentric Model
http://astro.unl.edu/classaction/loader.html?filename=an
imations/renaissance/ptolemaic.swf&movieid=ptolemaic
&width=900&height=660&version=6.0.0
According to the Heliocentric model
http://astro.unl.edu/classaction/loader.html?filename=an
imations/renaissance/venusphases.swf&movieid=venusp
hases&width=870&height=600&version=6.0.0
Galileo's Observations
Moons around Jupiter
http://www.youtube.com/watch?v=SsWMaAF0kmU
Galileo’s Observations
Ears on Saturn
(it’s rings)
http://www.redorbit.com/news/video/space_2/2585
749/are_saturns_rings_disappearing/
Galileo’s Observations
Stars in the Milky Way
FUN FRIDAY
Carl Sagan on the history of Astronomy
http://www.youtube.com/watch?v=IEhDkKfkWo
I&feature=fvsr