Chapter 20 Notes: Solar System
The Solar System
 Solar System is heliocentric
 Earth and other planets revolve around the Sun.
 Solar System Parts
 Sun
 Planets
 Four Inner Planets
 Four Outer Planets
 Comets, Asteroids, Meteors
 The Sun
 It is our most important star.
 Made up of ¾ hydrogen, ¼ helium.
 Has two major parts
 Interior
 Atmosphere
Sun’s Interior
 Interior has 3 Layers
 Core
 Radiation Zone
 Convection Zone
 The Core
 Inside of interior
 Where Sun produces its energy
 Nuclear Fusion takes place
gravity
H+H+H+H
He + Energy, Light, and Heat

Temperature Increases
 15,000,000 oC
 Radiation Zone
 Middle Layer of interior
 Area of very tightly packed gas
 Energy transferred mainly by electromagnetic radiation
 So dense it can take 100,000 years for energy to move through
 Convection Zone
 Outside layer of interior
 Hot gases rise from bottom of zone and cool at top
 Cool gas sinks then reheats and hot gas rises
 Convection Current: moves energy toward the Sun’s surface
Sun’s Atmosphere
 Sun’s



atmosphere has 3 layers
Photosphere
Chromosphere
Corona
 Photosphere
 Photo means light: Light Sphere
 This is the visible layer of the Sun
 Called the “surface of the Sun”
 looks like a restless boiling pot of liquid
 NOT A SOLID SURFACE
 Temperature is less than 6000 oC
 Chromosphere
 Chromo means color: color sphere
 Red/Pink Color
 Seen at the beginning and end of a total solar eclipse
 Corona
 Corona means crown
 Looks like a white halo
 Only seen during a total solar eclipse
 extends millions of kilometers into space as solar wind
Features of the Sun
 Sunspots: areas of gas on the Sun’s surface that are cooler than the gases around
them.
 Cool areas don’t give off much light
 Appear dark
 The number varies over an 11 year time period
 Shows Sun also on an axis
 Prominences: huge reddish loops of gas
 Often connect sunspots
 Can extend over the edge of the Sun
 Solar Flares: eruptions in the sunspots that release energy into space
 Can interfere with communication on Earth
 Short duration
 Solar Wind: Continuous stream of high energy particles released into space by corona
 Causes the auroras
 Increased by increasing solar flare strength
Inner Planets
 Terrestrial planets

Small and dense
 Rocky Surfaces
 Closest to Sun
 4 inner planets
 Mercury
 Venus
 Earth
 Mars
Outer Planets
 Gas Giants
 Very Large
 No Solid Surfaces
 Many Moons
 Rings: thin disk of small particles of ice and rocks
 4 Outer Planets
 Jupiter
 Saturn
 Uranus
 Neptune
 Pluto
 Not considered a planet any more
 Solid Surface
 Smaller and denser than Earth
 Other Objects in Space
 Comet: loose collection of ice, dust, and small rocky particles whose orbit is long
and narrow ellipses.

Asteroid: Rocky objects that are orbiting around the Sun
 too small and numerous to be planets

Meteoroid: chunk of rock or dust in space

Meteor: streak of light in the sky produced by burning of meteoroid in Earth’s
atmosphere.