Note that the following lectures include animations and PowerPoint effects such as fly-ins and transitions that require you to be in PowerPoint's Slide Show mode (presentation mode).

1
Note that the following lectures include
animations and PowerPoint effects such as fly-ins
and transitions that require you to be in
PowerPoint's Slide Show mode (presentation mode).
0
2
Here and Now
0

• Chapter 1

3
Guidepost
0

• As you study astronomy, you will learn about
  yourself. You are a planet walker, and this
  chapter will give you a preview of what that
  means. The planet you live on whirls around a
  star drifting through a universe filled with
  other stars and galaxies, results of billions of
  years of events and evolution. You owe it to
  yourself to know where you are in the universe
  because that is the first step to knowing what
  you are.
• In this chapter, you will meet three essential
  questions about astronomy
• Where are you in the universe?
• How does your life span and human history fit
  into the age of the universe?
• Why should you study astronomy?

4
Guidepost (continued)
0
As you study astronomy, you will see how science
gives you a way to know how nature works. In this
chapter, you can begin thinking about science in
a general way. Later chapters will give you more
specific insights into how scientists work and
think and know about nature. This chapter is a
jumping-off place for your exploration of deep
space and deep time. The next chapter continues
your journey by looking at the night sky as seen
from Earth.
5
Where are You?
0
To find our place among the stars, we will zoom
out from a familiar scene, to the largest scales
in the universe.
From each frame to the next, we zoom out by about
a factor 100.
6
A Campus Scene
0
16 x 16 m
7
A City View
0
1 mile x 1 mile
8
The Landscape of Pennsylvania
0
100 miles x 100 miles
9
The Earth
0
Diameter of the Earth 12,756 km
10
Earth and Moon
0
Distance Earth Moon 384,000 km
11
Earth Orbiting Around the Sun
0
Distance Sun Earth 150,000,000 km
12
Earth Orbiting Around the Sun (2)
0
In order to avoid large numbers beyond our
imagination, we introduce new units
1 Astronomical Unit (AU) Distance Sun Earth
150 million km
13
The Solar System
0
Diameter of Neptunes orbit Approx. 60 AU
14
(Almost) Empty Space Around Our Solar System
0
Approx. 10,000 AU
15
The Solar Neighborhood
0
Approx. 17 light years
16
The Solar Neighborhood (2)
0
New distance scale 1 light year (ly) Distance
traveled by light in 1 year 63,000 AU 1013
km 10,000,000,000,000 km ( 1 13 zeros) 10
trillion km
Nearest star to the Sun Proxima Centauri, at a
distance of 4.2 light years
Approx. 17 light years
17
The Extended Solar Neighborhood
0
Approx. 1,700 light years
18
The Milky Way Galaxy
0
Diameter of the Milky Way 80,000 ly
19
The Local Group Our Cluster of Galaxies
0
Distance to the nearest large galaxies several
million light years
20
The Universe on Very Large Scales
0
Clusters of galaxies are grouped into
superclusters. Superclusters form filaments and
walls around voids.