Download Planet Tour

GRADES
Moon Project
To give you a chance to do a good Moon
project I have changed the due date to
Wednesday, March 3. I have put a new sky
map for this period on the course web page
and Angel. Download and print it to use for
this part of the project.
Announcements
• Planet Assignment 2, due Monday Feb 23,
is on Angel (later tonight). First view the
movie “Formation of the Solar System” on
Astronomy Place to help you answer the
questions.
• Planet Assignment 3, due Wednesday Feb
25, is Astronomy Place tutorial “Formation
of the Solar System”
Exam Answers
• Will be posted on the course web page with
links from Angel Syllabus page tomorrow.
• Tonight we will go over some of the more
confusing questions.
What is a FACT &
what is a THEORY?
A FACT is a statement about an
observation - e.g. planets move on
elliptical orbits.
A THEORY is an explanation - e.g.
a = F/m
This is an explanation of why
things move the way they do. It
needs to be verified by tests.
Retrograde Motion
• Geocentric model uses
epicycles
• Heliocentric models
all rely on inner
planets moving faster
than outer planets and
overtaking them. No
epicycles in
heliocentric models.
Mars
Earth
Sun
Phase of Earth from Venus
Earth
Venus
Model Sun = grapefruit
• Recall map you made for homework
Model Milky Way = Earth-Sun
• Recall in this model distance to nearest star
is Washington DC to San Francisco
Force of Gravity
F = G M m / D2
• If D -> 1/2 Do, F -> 4 Fo
• If M -> 1/2 Mo, F -> 1/2 Fo
You see First Quarter Moon
in the WEST
• Moon must be setting
• 1Q Moon sets at midnight
Which has the most total Energy,
2
E=mc
• When you are high and fast have lots of
both gravitational PE and KE
• When plummeting to Earth, have converted
gravitational PE to KE
• If sitting in a hanger have least energy
Spaceship Earth
What are the motions of spaceship Eearth?
• Earth SPINS on its axis towards the EAST
once every 24 hours
• Earth ORBITS around the Sun
once every 365.25 days. Speed ~ 1x105 km/hr.
• Earth, the Sun & the Solar System all orbit around
the center of the Milky Way galaxy once every
2.3x108 years. Speed ~ 8x105 km/hr.
• The Milky Way is moving toward the Andromeda
galaxy, speed ~ 3x105 km/hr
• The Milky Way (along with the local group)
partakes in the expansion of the universe.
Simplest Model of Solar System
• Which is simplest depends on your taste,
but the most complicated is the Geocentric
model. Any of the other three got credit.
• We didn’t discuss the geocentric model in
detail so I dropped this question.
Spectrum in terms of Wavelength
• Increasing Energy = Decreasing
Wavelength
• Highest energy = shortest wavelength =
x-rays or gamma-rays.
Lowest energy = longest wavelength =
radio waves
Solar System(s)
Trivia
Patterns
What does the solar system
look like?
Sun
Over 99.9% of
solar system’s
mass
QuickTime™ and a
TIFF (Uncompressed) decompressor
are needed to see this picture.
Mercury
A hot rock
Qu ickTime ™ an d a
TIFF (U nco mpre sse d) d ecom pre sso r
are nee ded to s ee this p icture.
QuickTime™ and a
TIFF (Uncompressed) decompressor
are needed to see this picture.
Venus
The cloudy planet
QuickTime™ and a
TIFF (Uncompressed) decompressor
are needed to see this picture.
Venus
The cloudy planet
QuickTime™ and a
TIFF (Uncompressed) decompressor
are needed to see this picture.
Surface is hotter
and smoother than
Mercury’s
Venus
The cloudy planet
QuickTime™ and a
TIFF (Uncompressed) decompressor
are needed to see this picture.
Surface is hotter
and smoother than
Mercury’s
It’s another rock
Earth
The water planet
Earth
The water planet
The double planet
QuickTime™ and a
TIFF (Uncompressed) decompressor
are needed to see this picture.
Earth
The water planet
The double planet
Two more rocks
QuickTime™ and a
TIFF (Uncompressed) decompressor
are needed to see this picture.
Mars
A frozen planet
QuickTime™ and a
Sorenson Video decompressor
are needed to see this picture.
Mars
A frozen planet
Also a rock
QuickTime™ and a
TIFF (Uncompressed) decompressor
are needed to see this picture.
Mars
A frozen planet
Also a rock
QuickTime™ and a
TIFF (Uncompressed) decompressor
are needed to see this picture.
QuickTime™ and a
TIFF (Uncompressed) decompressor
are needed to see this picture.
Asteroid Belt
Lots more rocks
40 km
Jupiter
A gaseous planet
Not a rock!
Jupiter
A gaseous planet
Not a rock!
Jupiter
A gaseous planet
Not a rock!
QuickTime™ and a
GIF decompressor
are needed to see this picture.
Jupiter’s Moons
Io
Europa
QuickTime™ and a
TIFF (Uncompressed) decompressor
are needed to see this picture.
Ganymede
Four largest
discovered by
Galileo
Worlds of ice and
rock
Callisto
Io’s sulfur volcanoes
Europa’s Icy
Surface
QuickTime™ and a
TIFF (Uncompressed) decompressor
are needed to see this picture.
Saturn
QuickTime™ and a
TIFF (Uncompressed) decompressor
are needed to see this picture.
QuickTime™ and a
TIFF (Uncompressed) decompressor
are needed to see this picture.
Giant and
gaseous like
Jupiter
Saturn
Rings are made
of ice chunks
Artist’s conception
Uranus
The tilted planet
Also giant and
gaseous
Uranus
The tilted planet
QuickTime™ and a
YUV420 codec decompressor
are needed to see this picture.
Also giant and
gaseous
Has many moons
Neptune
Almost a twin of
Uranus (except
for the tilt)
Pluto
A dirty ball of ice
QuickTime™ and a
TIFF (Uncompressed) decompressor
are needed to see this picture.
Pluto’s moon
Charon is not
much smaller
Comets
QuickTime™ and a
TIFF (Uncompressed) decompressor
are needed to see this picture.
Also dirty balls
of ice
Comet Hale-Bopp
Spend most of
their time in solar
system’s outer
reaches
Have elongated
orbits
QuickTime™ and a
TIFF (Uncompressed) decompressor
are needed to see this picture.
Comet Wild 2
What features of our solar
system provide clues to how it
formed?
Terrestrial Planets: Four rocks close in
Jovian Planets: Four gas balls farther out
Pluto: An icy oddball
Virtually all rotational
motion in same direction
(Right-hand rule)
Rocky asteroids
between Mars & Jupiter
Icy comets in vicinity
of Neptune
More icy comets far
beyond Pluto
Exceptions to the
basic patterns
Four Big Questions
1) Why does virtually everything in the solar
system rotate in the same direction?
2) Why are the inner worlds rocky and the outer
ones gaseous or icy?
3) Where did the comets and asteroids come
from?
4) How can we explain the exceptions?