# Astronomy CN 2012

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```					Astronomy

Chapter 22-25
Warm Up: Sept 7
KGqIU – creepy twinkle
pAuU –cute twinkle
 Compare and contrast each version using
a Venn Diagram
 Which one do you like more? Why?
 Which one best describes human curiosity
towards outer space? WHY?         2
Time Line
   Create a time to include each of the following
people (include their discovery).
   Aristotle
   Eratosthenes
   Hipparchus
   Aristarchus
   Claudius Ptolemy
   Nicolaus Copernicus
   Tycho Brahe
   Johannes Kepler
   Galileo Galilei
   Sir Isaac Newton
What is the Golden Age of
Astronomy?
   The shift away from
the idea of a
Geocentric Universe.
What is Modern Astronomy?
   Nicolaus Copernicus
(1473-1543)
   Earth is just a planet
   Universe is sun centered
   Mercury, Venus, Earth, Mars,
Jupiter, and Saturn
   Circular orbits around sun
   Tycho Brahe (1546-1601)
   Used pointers to estimate
distance
   Pointers think big
protractor
   Mentor Kepler
Who was Johannes Kepler
(1571-1630)?
   Brahe’s observations of Mars
 Noticed that the orbit was not Circular
 Kepler used his Q&A’s to form 3 Laws of
Planetary Motion
   1st Law
   Ellipse (Oval)
2   foci
   Star
Laws of Planetary Motion
   2nd Law
   Sun sweeps over
equal areas in the
same amount of time.
   Close to sun faster
   Away from sun slower
   3rd Law
   Orbital Period (time) of
planet is proportional
to distance from the
sun (P2=d3),
expressed in AU units
(1AU = 1.5Million Km)
Who is Galileo Galilei?(1564-
 Telescope
1642)
   Behavior of moving objects
   Observation supported Copernicus’s view of the
universe
 Moons   of Jupiter (4) = Earth is not the center of all
universal motion
 Planets are circular disc = must be Earth-like
 Venus has phases like the moon = orbits light source
(sun)
 Moon’s surface not smooth = validated others who
named areas based on features (Sea of Tranquility)
 Sun has dark regions = tracked movement est.
rotation period of sun under 1 month
What is the Law of Universal
Gravitation?
   Sir Isaac Newton (1642-1727)
 Kepler “some force pushes the planets along their
orbits”
 Galileo “no force is required to keep an object in
motion”
   Inertia
   Every body attracts directly proportional to
mass & inversely proportion to distance2 b/w
the bodies
   Revised Kepler’s 3rd law (mass)
What are Earth Motions?
   Rotation
   Spinning on axis (day/night)
 Solar   day
   noon to noon
 Sidereal   day
   Based on a distant star
 23hr 56 min
 Distance to the stars change by tiny increments
 Sun changes by 1° a day
Earth Motions Cont.
   Revolution
   Moving around another body
 Distance   of the sun to the Earth @150 million km
 Elliptical Orbit
   Perihelion @ January 3
 147 million km
   Aphelion @July 4
 152 million km
Earth Motions Cont.
   Precession
   Change in tilt of axis
   23.5° always the same
   Slow @ 26 000 years
   Changes North Star
   Polaris to Vega
   Nutation
   Wobbling around the axis
   Caused but the moon’s pull
   Slight seasonal change.
   Remember: Galaxies on the move!
What are Axis & Seasons?

Why do different season exist?
Axis & Seasons cont.
Moon (Satellite) Motions
 Revolution = 1month (29 ½ days)
 Ave. distance = 384 401Km (6%)
 Perigee = closest to Earth
 Apogee = farthest

   Phases of the Moon
 Waxing
 Waning
How do Eclipses work?
What is Barycenter?
   The center of mass is the balance point
between two orbiting bodies, like a
seesaw.
The Sun
   Average Star
   Some Stats:
   Diameter = 109
Earth diameters
   Volume = 1.25
million times Earth’s
   Mass = 332,000
times Earth’s
   Density = 1/4th of
solid Earth
Sun Structure
   Structure
   the Solar Interior
   Photosphere
   2 Atmospheric Layers
   Chromosphere
   Prominences
   Corona
   Solar Winds
Solar Flares & Sunspots
   Solar Flares
   Auroras
   Sunspots
 11 year cycle
 Last days to weeks
The Solar interior
   Nuclear Fusion
   E=mc2
   It takes very little
hydrogen to make a
lot of energy.
   Most of the hydrogen
is not converted to
energy.
Other Stuff
   Scientific Methods Quiz Redo
   A problem is a question to be answered!!!!!
   Do not for get the problem/hypothesis relationship!!!!!
 Example Problem:
Does the presence of grain-eaters in the desert environment
cause a decrease in wildflower diversity?
 Example Hypothesis:
If grain-eaters are eliminated from the environment by a
fence, then the wildflower diversity will increase by 20%.
   Independent Variable
   Dependent Variable
   Write so anyone knows what you are saying!!!!!!!
Other Stuff
   13-14 = Awesome Job!!
   11-12 = Good, but needs some work.
   7-10 = OK, but what are you at a loss about?
   0-6 = Get help before the test Wednesday!!!
   19-20 = Stellar Performance!!
   18 = Awesome Job!!
   15-17 = Good, but needs some work.
   9-14 = Ummmhhhh I think you need to study!!!
   Below a 9= Seek help before Wednesday test!!!
The Golden Age Astronomers

Aristarchus
(312-230BC)

Aristotle
(384-322BC)

The Earth
is round.
1st to believe in
heliocentric
universe

```
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