Lesson 1-0
The Cosmic Landscape
Preface overview
 The Earth and Moon
 The planets
 The Sun
 Our solar system and galaxy
 Gravity—the universal force
The Cosmic Landscape
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Motivation
Earth and Moon are
part of a much
larger system.
The Cosmic Landscape
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Lesson overview
 What other planets orbit our Sun?
 How big is the Sun?
 What makes up our solar system?
 How can we measure distances?
 What is the Milky Way?
 What is your universal address?
 What force holds our universe together?
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Introduction
 Astronomy—what
is it?
 What do we find in
space?
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What other planets orbit our Sun?
 Eight planets—Earth and its sister planets
 In order from the Sun: Mercury, Venus, Earth, Mars,
Jupiter, Saturn, Uranus, Neptune
Sun
 Pluto is recognized as a “dwarf” planet, but not like the
other eight planets
 a Most people wonder about certain planets because of
their position or size.
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What other planets orbit our Sun?
(cont’d)
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How big is the Sun?
 Big compared to other planets
 Very big compared to Earth
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How big is the Sun? (cont’d)
 Relative sizes—
Sun and planets
compared to
common objects
 100 times
Earth’s diameter
Sun
Jupiter
 300,000 times
Earth’s mass
 Why so big?—
different from
the planets
The Cosmic Landscape
Earth
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What makes up our solar system?
 The Sun
 Nine planets
 Satellites (moons)
 Asteroids and comets
Asteroid belt
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How big is space?
 Space is gigantic! Distances are mind-boggling
 Sun to Pluto: 4 billion miles
 Sun to Earth: 93 million miles
 Sun to Mercury: 37 million miles
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How can we measure
huge distances?
 A clue—the common flashlight
 Speed of light—a way to measure
distances in space
 300,000 kilometers per second
 186,000 miles per second
 670,000,000 miles per hour
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How can we measure
huge distances? (cont’d)
 Distances as time—weird idea or pretty
common?
 For space, a bigger measure: the light
year
 About 6 trillion miles!!
 If you traveled the distance of a light year,
and you went at 1 mile per second, it would
take you 186,000 years!!
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What is the Milky Way?
 A galaxy
 One of many galaxies
 Part of visible
universe
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What is your universal address?
 Find our solar system in the Milky Way
We’re here: 93
million miles
from the Sun.
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What is your universal address?
(cont’d)
 Locate the Milky Way galaxy in the Local
Group.
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What is your universal address?
(cont’d)
 Look at our Local Group and Local
Supercluster.
We are here.
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What is your universal address?
(cont’d)
So your universal address is:
Your name
Your street address
Your city and state, zip code
United States of America
Planet Earth
Our Sun’s solar system
Milky Way galaxy
Local Group
Local Supercluster
Universe
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What force holds
our universe together?
 Understanding the gravity of our
situation
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Lesson review
 What planets orbit our Sun?
 Nine planets
 How big is the Sun?
 Much bigger than—and different from—the planets
 What makes up our solar system?




The Sun
Nine orbiting planets
Moons
Asteroids and comets
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Lesson review (cont’d)
 How can we measure huge distances in
space?
 The light year
 What is the Milky Way?
 A galaxy that fits into parts of the visible universe
 What is your universal address?
 Starts with your name, ends with the universe
 What force holds the universe together?
 Remembering the gravity of your situation
The Cosmic Landscape
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