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Our Solar System
Chapter 14
Astronomy – A historical perspective
• Been studied for 1000’s of years
• 125 BC Hipparchus, Greek Astronomer,
arranged stars according to brightness
• 140 AD Geocentrism – believed that the center
of our solar system is the Earth.
• This lasted 1400 yrs
• Early 1500’s Copernicus proved the Heliocentric
model – the sun is the center of our system
• 1600’s Galileo proved Copernicus’ theory
• 1610 Galileo discovers that Venus goes
thru phases and that Jupiter has 4 moons.
• Kepler-used Tycho Brahe’s data to
develop 3 laws for planetary motion
– #1 Planets orbit in ellipses
– #2 Each planet moves faster when closer to
the sun & slower when further away
– #3 Planets closer to the sun orbit faster than
the planets further away
• 1781 Uranus discovered
• 1961 Soviet cosmonaut 1st to orbit the
Earth
• 1981 1st space shuttle launch
• 1994 Comet Shoemaker-Levy 9 crashes
into Jupiter
• 1998 Russia & US begin construction of
International Space Station
• 2006 Pluto “deplanetized”
Our Solar System
Made of: sun/stars, planets, other bodies
that travel around it
*It is a mixture of Gas & Dust*
How did it begin?
Theory
Nebula – a HUGE clump of gas/dust
which collapses upon itself
This forms “planetesimals” which are the
building blocks of planets
Big Bang 
Nebula, large
mass of gas
and dust,
swirling
counter clockwise forming
planets out of
planetesimals,
creates our
galaxy the
Milky Way.
The Big Bang – A Theory
A long time ago,
(10 – 15 billion yrs ago) there once
was an empty place. This place began
filling up with small particles (atoms, gases, etc).
They finally created enough energy to break the
gravitational hold on them and EXPLODE. The
scattered particles cool down over time and form
what we know today as our planets, stars,
asteroids, etc. = Universe (containing our
galaxy the…
Milky Way.
The Milky Way – 4.6
billion yrs old
The Sun –Our Star
A large ball of gas (Hydrogen and Helium) held
together by gravity
The Sun makes its energy thru – Nuclear Fusion.
This is where 2 or more nuclei join together, or
fuse, to make a larger nucleus (Einstein figured
this out)
A LOT OF ENERGY IS CREATED
It takes approx 8 minutes for the sun’s energy to
arrive here on Earth.
The Sun’s Structure
6 Layers
1. Corona
Only visible during a total solar eclipse and can
reach temps up to 2,000,000ºC
2. Chromosphere
Very thin region with
temps 4,000 –
50,000ºC
(sometimes called the
dancing layer)
3. Photosphere
The yellowish surface of the sun
4. Convective Zone
Very thick region; hot and cool gases
moving around (hot out and cool in)
Prominence’s created from within
the Convective Zone
5. Radiative Zone & 6. The Core
Very dense gas that it
cannot be seen thru;
light takes millions of
years to get from one
side to the other.
Center of the sun where
energy is created;
temp = 15,000,000ºC
1. Core
2. Radiative Zone
3. Convective Zone
4. Photosphere
5. Chromosphere
6. Corona
Prominences – huge reddish loops of gas often linking different parts of
sunspot regions.
Features on the Sun
• Sunspots – cool, darker
spots on the sun
• Prominence-huge reddish
loops of gas, a group of
sunspots
•Solar Flares – giant storms with temps up to
5,000,000ºC (can cause electrical disturbances
here on Earth)
Measuring the distance from the Sun
• One astronomical unit (AU) equals Earth’s
average distance from the sun
• 1 AU= 150 million Km
• Speed of Light = 300,000km/s
• A light year = the distance that light can
travel in a year (or around the world 7 and a
half times in one sec)
• Auroras- Particles
created by solar flares
react with Earth’s
atmosphere causing
spectacular light
Solar wind- A stream of
shows
electrically charged particles
that emanate from the sun’s
corona can cause magnetic
storms on Earth & disrupt radio,
telephone, & TV signals, & can
cause electrical power problems
The Planets
The Terrestrial Planets
(Inner Planets)
• Mercury
• Venus
• Earth
• Mars
• The Outer Planets
• Jupiter
• Saturn
• Uranus
• Neptune
• Pluto 
The Earth – Our Home
Some facts:
• Rotates with a speed of 65,000
mph (105,000 kmph)
• The distance from the Earth to the
Sun is an avg 91,402,300 miles
(147,097,800 km)
The Earth
3 Layers of the Earth
1. Crust – 5-100km thick; (a very thin outer
layer)
2. The Mantle
Extends from about 100km to 2900km; more
dense than the crust.
3. Core
In the center of the
Earth; approx
6400km below the
Earth’s surface; it
makes up 1/3 of Earth’s
mass.
Earth’s Atmosphere Composition
1st Atmosphere:
Composed of Hydrogen (H), Methane,
Ammonia, and Water.
This atm was possibly created by crashing comets.
They brought water with them from space. The
volcanoes that were erupting produced a lot of
water vapor.
Early oceans acted as the “Primordial (original)
Soup” from which came LIFE.
Today’s Atmosphere:
21% Oxygen, 76% Nitrogen, 1% Argon,
and tiny amounts of many other gases.
A curved view of our atmosphere
The 9 Planets
of our Galaxy (June 2006)
Mercury
Venus
Earth
Mars
Jupiter
Saturn
Uranus
Neptune
Pluto 
Comets
• A loose collection of ice,
dust, & small rocky particles.
They orbit in long, narrow
ellipses.
• Comet parts
– Coma-fuzzy outer layer from
the sun turning the ice to gas
– Nucleus- the solid inner core of
the comet
– Tail-2 parts, gas and dust, can
be more than 100 million km
long
Asteroids
• Small rocky space objects
• Orbit around the sun in the asteroid belt
between Mars and Jupiter
– most orbit in circular orbits
– Some have elliptical orbits and get closer to
the sun than earth
Meteors
• Meteroid- chunks of rock or dust in space
– Originate from comets or asteroids
• Meteor-a meteroid that burns as it enters
the Earth’s atmosphere and creates a
streak of light
• Meteorite-meteoroids that pass through
the earth’s atmosphere and strike the
earth’s surface