Download Document

Week 8.5
9th grade science
Must Do
 Make a list of all of the characteristics of the solar
system you can think of.
 Think about…





Planets & moons
Temperature
Motion and direction
How it is layed out
Astroids and comets
Objectives
 Summarize the major features that a theory of solar
system origins has to explain.
The Formation of the Solar
System
 There are nine outstanding properties of our solar
system that any formation theory must be able to
explain. In your table groups, see how many you
can come up with.
Each planet is relatively
isolated in space.
 Planets are independent bodies that are not
bunched together.
 In rough terms, each planet tends to be twice as far
from the sun as its inward neighbor.
The orbits of the planets
are very nearly circular
 With the exception of Mercury and Pluto each
planetary orbit closely describes a perfect circle.
The orbits of the planets all lie
in nearly the same plane.
 Within a few degrees. With the exception of
Mercury and Pluto
The direction in which the planets orbit the
Sun is the same as the direction in which
the Sun rotates on its axis.
 Counterclockwise as viewed from above the north
pole.
 Virtually all motion is on the same plane as the
earths equator and in the same direction as the
Sun’s rotation.
The direction in which most planets rotate
is roughly the same as the direction the
Sun rotates
 …except Venus, Uranus, and Pluto
Most moons revolve about their planets in
the same direction the planets rotate.
Our planetary system is highly
differentiated
 Inner planets are characterized by high densities
and moderate atmospheres, slow rotation rates, and
few or no moons.
 The jovian planets are further from the sun have
low densities, thick atmospheres, rapid rotation
rates, and many moons.
Asteroids are very old and exhibit a range
of properties differing from our planets
and moons
 Share similar orbital properties as the planets.
 Made of primitive unevolved material, meteorites
that strike Earth are the oldest rocks known.
Comets are primitive icy fragments that do
not orbit in the elliptical plane and are far
from the Sun