Chapter 14- The Solar System
CUE WORDS or QUESTIONS
How is our solar system
organized?
What is an astronomical unit?
NOTES WRITTEN
Geocentric- Earth is the center of the solar system and everything revolves
around us (developed by Ptolemy)- old model
Heliocentric- Sun is the center of the solar system and everything revolves
around the sun (developed by Galileo)- current model
Our solar system consists of the sun, the planets and their moons,
and all the objects that orbit around the sun
Astronomical unit (au)- unit used to measure distances within our solar
system
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What is the sun?
How does the sun make
energy?
What are the layers of the
sun’s atmosphere?
What are the features of the
sun?
SUMMARY
Equals the distance from Earth to the sun (150 million km)
The sun contains 99.8% of all of the mass of the solar system and so has
a very strong gravitational force
The sun is a giant ball of gas that provides energy and light for life on
earth via nuclear fusion
Nuclear fusion- fusion of the nuclei of atoms to form larger elements, energy
is released in the process
Hydrogen fusion- type of nuclear fusion, hydrogen atoms fuse to form helium
atoms (stars spend 90% of their lives doing this)
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Nuclear fusion occurs only in high temperature and pressure (it
only occurs in the core)
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The outward force of pressure balances with the inward force of
gravity (otherwise the sun would explode!)
 Stars emits light, all other objects in space reflect light
Sun’s atmosphere (in order from the surface to the outermost layer):
1) Photosphere- part of the sun you can see
2) Chromosphere- reddish glow only visible during a solar eclipse
3) Corona- white halo around the sun that extends for millions of km
Features of the sun:

Sun spots- areas of cool gas on the photosphere that appear dark,
caused by intense magnetic activity (the number of sunspots vary
every 11 years and effect Earth’s temperature)
CUE WORDS or QUESTIONS
What is the difference between
the inner and outer planets?
NOTES WRITTEN
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Prominences- huge red loops that link different sunspots
Solar flares- large amounts of thermal energy ejected from the
prominences
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Solar wind- particles of energy ejected from the sun
Inner planets (terrestrial planets):
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Small
Dense
Solid
No rings
Little to no atmosphere
Outer planets (gas planets):
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What are characteristics of
comets, asteroids and
meteoroids?
Mercury- Venus- Earth- Mars
Jupiter- Saturn- Uranus- Neptune
Large
Less dense (because they are made of gas)
Gas
Rings
Large atmosphere
Comets- collections of ice, dust and rock that orbit in long, narrow ellipses
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Tail is always facing away from the sun
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Tail can be as long as 100 million km long
Most comets are from the Kuiper belt or the Oort cloud
Asteroids- rocky objects that are too small to be planets

Most are found in the asteroid belt between the inner and outer
planets
Meteoroids- chunk of rock/dust in space, left over from asteroids & comets
SUMMARY
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Meteor- light produced as the meteoroid hits the atmosphere
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Thousands of meteors hit earth each day
Meteorite- meteoroids that hit Earth’s surface (they are not broken up
by the atmosphere)