Download Solar System

Universal
Gravitation
Any two masses m1 and
m2 separated by a
distance R are
attracted by a force
given by
F = G (m1 m2) / R2
G = 6.67 x10-11 Nm2/kg2
g = 9.8 m/sec2
Solar System
Terrestrial Planets and
Comparative Planetology
Variety of Planets

Why so different?

“Terrestrial” planets

“Jovian” planets
(=Terr + gas!)

The physics….
neat stuff…
Neat stuff to understand

What is meant by an atmospheric gas’
“temperature”?

Does “what goes up” have to come down?
Let’s see…
Put them
together
For planets plot
vesc vs. temp
For gases plot
<v> vs. temp
Problems with
extrasolar gas
giants.
The Earth

Famous
picture

Oblateness
of 0.0034
(demo)

Average
density is
~5.5 g/cm3
Whereas
surface
rocks ~3…
Seismology tells of interior
Waves from
earthquakes
refracted at
boundaries
 Liquid and
solid inner
cores
 Rotation of
liquid core
leads to …

Magnetic Field

Permanent
magnet
possible?

Alternative:
currents…
Magnetic Field

“Dynamo”
action of
rotating liquid
core

Charged
particles in
liquid core
move (and
moving
charges = a
current)
Interior structure



Core heated in
formation, kept hot
from natural
radioactivity
Cools slower than
smaller bodies like
the Moon and
Mercury (& babies)
Convection of
lithosphere leads to
seismic events and
plate tectonics…
Plates of the Earth
Action occurs along plate boundaries…
Volcanoes
Mt. St. Helens…
Island Strings
Hawaiian
Islands
How formed?
Hot Spots + Plate Motion

xx
Earthquakes
Continental Drift
If we back up…
Pangaea – 260 million years ago
Tides
Differential
gravitational
force
 The Moon is
twice as
important as
the Sun
 Result…

Tidal distortion
Earth itself
stretches about 9
inches
 Tidal flow much
larger
 Two peaks (tides)
per day

Sun and Moon Together

“Spring” tides
when aligned

“Neap” tides when
perpendicular

Extra-high when
Moon near perigee
and/or Earth near
perihelion
Births and the Moon?
Has anyone
heard that
birthrates
depend on
the phase of
the Moon?
My Study
Nope.
Nor ….
… plotted against perigee