23.1 The Solar System
The Planets: An Overview
Terrestrial planets are relatively small and rocky
“Earth like”
Mercury
Venus
Earth
Mars
Jovian planets are huge gas giants
Jupiter
Saturn
Uranus
Neptune
Continued…
Pluto does not fit into either category (small &
cold)
Size is the most obvious difference between the
terrestrial & Jovian planets
The 4 Jovian planets & Pluto are further from the
sun they are called outer planets
The terrestrial planets that closer to the sun are
known as inner planets
Density, chemical makeup, & rate of rotation are
other ways that the 2 groups differ
The Interiors of the
Planets
TP are dense mostly containing rocky
metallic substances & minor amts. Of gases
& ices
JP contain large amts. of gases & ices
The substances that make up the planets are
divided into 3 groups:
Gases (MP -273 degree Celsius)
Rocks (MP above 700 degree Celsius)
Ices (Intermediate MP)
The Atmosphere of the
Planets
JP have a very thick atmosphere of hydrogen,
helium, methane, & ammonia
TP have smaller atmospheres
Planet’s ability to retain an atmosphere
depends on its mass & temp. (diff. in JP & TP)
Moon lacks an atmosphere
Formation of the Solar
System
Nebular Theory – the sun & planets formed
from a rotating disk of dust & gases
As the speed of the rotating disk increased the
disk began to flatten out.
Matter became more concentrated in this
center, where the sun eventually formed
Growth of the planets started as solid bits of
matter began to collide & clump together
(planetesimals)