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Chapter 6 The Solar System
Lesson 1: The Sun
Main Idea:
The Sun is a star made of hydrogen and helium. The Sun is locate at the center of
the solar system and also its largest object.
Vocabulary:
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Star (pg. 299) – A star is an object that produces it own energy including heat
and light.
Astronomical unit (pg 299) – The mean, or average, distance between the sun
and the Earth (1 AU = 149,591,000 km)
Fusion (pg 302) – Smashing together of particles.
What is the Sun?
Main Idea:
The sun is a star and the largest object in the solar system.
Supporting Detail:
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The sun is a star.
 A star is an object that produces its own energy including heat and light.
o The planets and other objects in the solar system are not stars
o They do not produce light.
 Sun is an averaged sized star.
Larger stars produce ten million times more energy.
Smaller stars produce 1 / 100th as much energy as the sun
The sun’s diameter is about 1,390,000 km (863,706 miles)
The mean, average, distance between the sun and the Earth is 149,591,000 km
(92,960,000 miles).
 One astronomical unit (AU) equals the average distance from the Earth to
the sun.
 Alpha Centauri are the closest stars to our solar system. They are about
271,931 AU away.
Sun’ s Mass
 The mass of the sun can be calculated if you take:
o Length of time it takes a planet to make one trip around the sun
o The average distance between the planet and the sun
 The sun’s mass is calculated to be 2 million trillion trillion kilograms
 The mass of the sun makes up 99.8% of all of the mass in the solar system.
What are the parts of the Sun?
Main Idea:
The sun is made up of three layers of gas surrounded by 2 layers of atmosphere.
Supporting Detail
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The sun is a huge sphere made up of:
 About 71% hydrogen
 About 27% helium
 About 2% carbon and oxygen
The sun has 3 layers of gas
 The core
o Is the center of the sun.
o produces most of the sun’s energy
o has temperatures of 10 million to 20 million degrees Celsius.
o It’s pressure is 1 billion times greater than the air pressure on Earth.
 The radiation layer
o is the inner layer.
o moves the energy produced in the core in every direction.
o can take millions of year for the energy in this layer to move out.
 The convection layer
o is the outer most layer.
o Gases with different energies move in circular patterns in this layer similar
to air with different densities.
o Energy moves out in about a week
The photosphere
 is the visible surface of the sun
 is not a solid surface, but rather layers of gases
 has a temperature of about 5,730 degrees Celsius.
Sun has two atmosphere layers
 Chromosphere
o Inner layer of the sun’s atmosphere
o Appears as the red circle around the sun
 Corona
o Outermost layer of the sun
o Takes on a different shape depending on changes in the photosphere’s
temperature
Solar flares
 Are bursts of heat and energy that stretches out from the corona and
chromosphere into space
 Can appear as different colored lights in the polar regions (aurora borealis)
 Are associated with sunspots, dark spots on the photosphere with lower
temperatures than areas around it.
How does the Sun produce energy?
Main Idea
The sun produces energy when hydrogen combines to form helium and energy.
Supporting Detail
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Einstein discovered a relationship between energy and mass and showed the
relationship in the following formula:
E = mc2
E – energy, m – mass, c – speed of light
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The equation tells us that a little bit of mass can be changed into a lot of energy.
Hydrogen particles in the sun smash together to form helium.
Fusion is smashing particles together.