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ASTRONOMY 112ASTRONOMY 112
Stars, Galaxies, and Stars, Galaxies, and CosmologyCosmology
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
The Nature of AstronomyThe Nature of Astronomy
““Looking at the stars always makes Looking at the stars always makes me dream- as simply as I dream over me dream- as simply as I dream over the black dots representing towns and the black dots representing towns and villages on a map. Why, I ask myself, villages on a map. Why, I ask myself, shouldn’t the shining dots of the sky shouldn’t the shining dots of the sky be as accessible as the black dots on be as accessible as the black dots on the map of France?”the map of France?”
Vincent Van GoghVincent Van Gogh18891889
The Nature of AstronomyThe Nature of Astronomy The inaccessibility of cosmic phenomena is The inaccessibility of cosmic phenomena is
one of the most intriguing features of the one of the most intriguing features of the study of astronomy study of astronomy
Although technology has greatly increased Although technology has greatly increased since the time of the ancients, astronomy since the time of the ancients, astronomy remains primarily a passive scienceremains primarily a passive science
Experimental, Empirical but Primarily Experimental, Empirical but Primarily Observational ScienceObservational Science
Still provides great insight into the origin, Still provides great insight into the origin, history, evolution, and underlying physics history, evolution, and underlying physics and chemistry of celestial phenomena and and chemistry of celestial phenomena and the universe itself…the universe itself…
The Nature of AstronomyThe Nature of Astronomy Since pre-history people have gazed into the Since pre-history people have gazed into the
sky and pondered the nature of the universe sky and pondered the nature of the universe All early civilizations studied the stars and the All early civilizations studied the stars and the
motions of the five naked-eye planets known to motions of the five naked-eye planets known to them as the “them as the “wandererswanderers” ”
They used their observations to tell time, for They used their observations to tell time, for navigation, to predict the coming of seasons, to navigation, to predict the coming of seasons, to explain eclipses, and to reinforce their religious explain eclipses, and to reinforce their religious beliefs beliefs
Now, we apply empirical methods of science to Now, we apply empirical methods of science to understand the physical nature of these understand the physical nature of these phenomenaphenomena
Now, we can explore with humans, robotically, Now, we can explore with humans, robotically, and passively from great distancesand passively from great distances
Pseudoscience vs. Real Pseudoscience vs. Real ScienceScience
Astronomy, By DefinitionAstronomy, By Definition Astrology, By DefinitionAstrology, By Definition Empirical Science vs. PseudoscienceEmpirical Science vs. Pseudoscience Scientific Models and TestingScientific Models and Testing
Astronomy, by DefinitionAstronomy, by Definition
the science concerned with the science concerned with celestial objects along with the celestial objects along with the observation and interpretation observation and interpretation of the radiation from the of the radiation from the component parts of the universecomponent parts of the universe
Astrology, by DefinitionAstrology, by Definition
the ancient belief that the positions the ancient belief that the positions of the sun, moon, and planets with of the sun, moon, and planets with respect to the zodiac influenced respect to the zodiac influenced earthly affairs and human livesearthly affairs and human lives
Astronomy, Astrophysics, Astronomy, Astrophysics, and Cosmologyand Cosmology
Golden Age of AstronomyGolden Age of Astronomy NASA’s Great ObservatoriesNASA’s Great Observatories Enormous telescopes worldwide and on orbitEnormous telescopes worldwide and on orbit New Generation of Extremely Large New Generation of Extremely Large
Telescopes PlannedTelescopes Planned Still, fundamental secrets of the universe Still, fundamental secrets of the universe
remain mysteriousremain mysterious The nature of dark matter, dark energyThe nature of dark matter, dark energy Era of the first starsEra of the first stars The evolving decelerating, then accelerating The evolving decelerating, then accelerating
universeuniverse
The Structure of the The Structure of the UniverseUniverse
Is the universe continuous, or Is the universe continuous, or discontinuous?discontinuous?
Is the universe homogenous or Is the universe homogenous or inhomogeneous?inhomogeneous?
Does the universe end?Does the universe end? Levels in the hierarchyLevels in the hierarchy Fundamental forces that govern everythingFundamental forces that govern everything GUTS and TOESGUTS and TOES Laws of physics are ubiquitousLaws of physics are ubiquitous
Hierarchy of the Hierarchy of the Distribution of “Luminous” Distribution of “Luminous”
MatterMatter From quarks to the cosmos…From quarks to the cosmos… 12 levels in the hierarchy…12 levels in the hierarchy… Fundamental ForcesFundamental Forces Cosmic Irony: The simplicity and Cosmic Irony: The simplicity and
complexity of the universe...complexity of the universe... Scale of the CosmosScale of the Cosmos Luminous matter does not include Luminous matter does not include
“dark” components“dark” components
Quarks: SN (10-16 meters)
Subatomic Particles: SN (10-15 meters)
Atoms: EM (10-13 meters)
Molecules: EM (10-9 meters)
Matter (stuff): Gravity (100 meters)
Planets: Gravity (107 meters)
Solar System: Gravity (1014 meters)
Star Clusters: Gravity (1018 meters)
Galaxies: Gravity (1020 meters)
Galaxy Clusters: Gravity (1021 meters)
Super Clusters: Gravity (1023 meters)
Universe: Gravity (1025 meters)
There are four fundamental forces in nature 1. Gravity 2. Electromagnetic (EM) 3. Strong Nuclear (SN) 4. Weak Nuclear
The Structure of Everything
p+ = 2 up + 1 down
n = 2 down + 1 up
The Nature of Space and The Nature of Space and TimeTime
Space and Time are Different Space and Time are Different Aspects of the Same PhenomenonAspects of the Same Phenomenon
Into the PastInto the Past Light Travel Time and the History of Light Travel Time and the History of
the Universethe Universe
Into the PastInto the PastTime 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
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