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

Scale of the CosmosScale of the Cosmos

Supplemental Presentation…Supplemental Presentation…

Powers of TenPowers of Ten

Supplemental Video…Supplemental Video…

Matter Energy

Dark Matter

Dark Energy

Space Time

The Universe in a Nutshell

and

Size of the UniverseSize of the Universe

Supplemental Presentation…Supplemental Presentation…

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