Transcript MoonPhases_Kepler

Path of the Sun project: Capri, Amy, Courtney?
Where someone says, or you read, that “the sun is overhead at
midday” is this strictly correct?
Review: Eclipses
What type of eclipse would be seen by observers on the night side of
the earth in this diagram?
A)
B)
C)
D)
Total solar eclipse
Total lunar eclipse
No eclipse
Partial lunar eclipse
And what is wrong with the way this picture is drawn?
Moon Phases: putting it all together
Another demo, with everyone out of your seat! Time for “moon
balls” demonstration
If tonight the moon is full when it rises in the east, what phase will it be
when it sets in the west?
A) Full
B) last quarter
C) New moon
D) First quarter
Lecture tutorial, p.81, Cause of moon phase
Now, back to motions of the Planets: Copernicus and Circles
Copernican theory: planets revolve around the sun, not around the earth
Let’s watch what you might observe for Venus, Mars
http://astro.unl.edu/naap/ssm/animations/configurationsSimulator.html
This was before the
telescope, so no
ideas about what
planets actually
looked like – just
points, like stars
Lecture-tutorial, p. 99, Observing Retrograde motion
Digress: what is a theory?
The word "theory" means something very different in
everyday language than it does in science: to the average
person, a theory is just an idea…
A scientific theory is an explanation of something that has
been demonstrated through repeated experiments or testing.
A scientific theory can also make predictions that can be
tested
What can we predict about the appearance of Venus when
seen through a telescope?
Galileo was the first to look at planets through a telescope.
These are views of Venus at different points in its orbit:
And again…
Kepler: planets move in almost circular orbits
Kepler lived at the same time as Galileo, both born
shortly after Copernicus published his book. He
used the careful observations made by Tycho Brahe
to modify Copernicus’ idea of circular motion.
He realized, from the orbit of Mars, that the planets
move not on circular, but in elliptical orbits.
You will also have a chance to explore these in a computer lab. The web
page looks like this:
Simulator, Worksheet for Kepler’s Laws
http://astro.unl.edu/naap/pos/animations/kepler.html
Review…
Kepler : provided understanding of motions of planets, and thus, every other
body in the universe in his three laws
1.
Planets orbit sun in ellipse
2.
Line connecting sun and planet sweeps out
equal areas in equal
3.
Period (“Year”) squared = semi-major axis
cubed
Wdefine the astronomical unit (a.u.), as the distance from
the sun to the earth
Next : Isaac Newton, explained Kepler’s
laws
Breakthroughs in mechanics, optics,
gravity, mathematics (invented
calculus)