1. ASTRONOMY 112 Stars, Galaxies, and Cosmology
INTRODUCTION
The Nature of Astronomy and Astronomy By Definition
Scale, Structure, and a Tour of the Universe
The Hierarchy of the Distribution of Matter
Fundamental Forces
The Seven Unique Things in the Universe
Scale of the Cosmos
Powers of Ten
Composition of the Cosmos
The Nature of Space and Time

2. The Nature of Astronomy
“Looking at the stars always makes me dream- as simply as I dream over the black dots representing towns and villages on a map. Why, I ask myself, shouldn’t the shining dots of the sky be as accessible as the black dots on the map of France?”
Vincent Van Gogh
1889

3. The Nature of Astronomy
The inaccessibility of cosmic phenomena is one of the most intriguing features of the study of astronomy
Although technology has greatly increased since the time of the ancients, astronomy remains primarily a passive science
Experimental, Empirical but Primarily Observational Science
Still provides great insight into the origin, history, evolution, and underlying physics and chemistry of celestial phenomena and the universe itself…

4. The Nature of Astronomy
Since pre-history people have gazed into the sky and pondered the nature of the universe
All early civilizations studied the stars and the motions of the five naked-eye planets known to them as the “wanderers”
They used their observations to tell time, for navigation, to predict the coming of seasons, to explain eclipses, and to reinforce their religious beliefs
Now, we apply empirical methods of science to understand the physical nature of these phenomena
Now, we can explore with humans, robotically, and passively from great distances

5. Pseudoscience vs. Real Science
Astronomy, By Definition
Astrology, By Definition
Empirical Science vs. Pseudoscience
Scientific Models and Testing

6. Astronomy, by Definition
the science concerned with celestial objects along with the observation and interpretation of the radiation from the component parts of the universe

7. Astrology, by Definition
the ancient belief that the positions of the sun, moon, and planets with respect to the zodiac influenced earthly affairs and human lives

8. Astronomy, Astrophysics, and Cosmology
Golden Age of Astronomy
NASA’s Great Observatories
Enormous telescopes worldwide and on orbit
New Generation of Extremely Large Telescopes Planned
Still, fundamental secrets of the universe remain mysterious
The nature of dark matter, dark energy
Era of the first stars
The evolving decelerating, then accelerating universe

9. The Structure of the Universe
Is the universe continuous, or discontinuous?
Is the universe homogenous or inhomogeneous?
Does the universe end?
Levels in the hierarchy
Fundamental forces that govern everything
GUTS and TOES
Laws of physics are ubiquitous

10. Hierarchy of the Distribution of “Luminous” Matter
From quarks to the cosmos…
12 levels in the hierarchy…
Fundamental Forces
Cosmic Irony: The simplicity and complexity of the universe...
Scale of the Cosmos
Luminous matter does not include “dark” components

12. Scale of the Cosmos
Supplemental Presentation…

13. Powers of Ten
Supplemental Video…

14. The Universe in a Nutshell
Matter
Energy
Dark Matter
Dark Energy
Time
Space
and

16. Size of the Universe
Supplemental Presentation…

17. The Nature of Space and Time
Space and Time are Different Aspects of the Same Phenomenon
Into the Past
Light Travel Time and the History of the Universe

18. Time required for light to travel to earth
Into the Past
Time required for light to travel to earth
Moon
1.25 seconds
Sun
8.5 minutes
Centauri
4.5 years
Betelgeuse
1,200 years
Milky Way
100,000 years
Andromeda
2.2 million years
Virgo Cluster
60 million years
Hydra Super Cluster
3 billion years
Quasars
13 billion years
Cosmic Microwave Background (CMB)
13.5 billion years