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Welcome to PHYS 1302Welcome to PHYS 1302
Astronomy of theAstronomy of they fy fSolar SystemSolar System
HomeHome
Everything on the screen is available to you on the class homepage:
Everything on the screen is available to you on the class homepage: www.sci.angelo.edu/phys1302
Everything is copyright (2009) for fair use in the classroom by registered students in the Fall 2009 term at Angelo State University
www.sci.angelo.edu/phys1302
Everything is copyright (2009) for fair use in the classroom by registered students in the Fall 2009 term at Angelo State University
What we’ll talk about todayWhat we’ll talk about today
IntroductionsIntroductions
S ll bS ll bSyllabusSyllabus
Schedule of weekly reading Schedule of weekly reading assignmentsassignments
Define basic tenets of science Define basic tenets of science
Dr. BlountDr. Blount
PersonalsPersonals onon thethe ProfProf::•• Corpus Christi native, 6Corpus Christi native, 6thth generation generation TejanoTejano•• Lived in Mineral Wells, Bremen, Bremerhaven, San Antonio, Austin, Alpine, El Lived in Mineral Wells, Bremen, Bremerhaven, San Antonio, Austin, Alpine, El
Paso, Arizona, North Dakota, Corpus Christi, San AngeloPaso, Arizona, North Dakota, Corpus Christi, San Angelo•• Del Mar College (75Del Mar College (75--79), CCSU (8179), CCSU (81--82)82)•• Sul Ross State (83Sul Ross State (83--85), UT85), UT--El Paso (85), Arizona State University (86El Paso (85), Arizona State University (86--88)88)
Trained as a Planetary Scientist:Trained as a Planetary Scientist:yyJim Whitford-Stark, Ron Greeley, Phil Christensen, Mike Malin, John Adams
TaughtTaught @@ UTUT--ElEl PasoPaso--8585GeologyGeology
UniversityUniversity ofof NorthNorth Dakota,Dakota, 8888--9393SpaceSpace ScienceScience
TexasTexas A&MA&M--CorpusCorpus Christi,Christi, 9393--0606EnvironmentalEnvironmental Science,Science, Geology,Geology, PhysicsPhysics
Dr. BlountDr. Blount
Personal webpage:• www.sci.angelo.edu/grady.htm
Attended 17 K-12 schools (Army brat)
Stubborn:• Took College Algebra twice
• Took Trig three times
• Got a “D” in English
• Have a Ph.D. and over $25M in grants
How about you?How about you?
Please take out a piece of paperand share with me the following:
• Your name?• Hometown?Hometown?• Why are you in this class?• What is your class (frosh, soph, etc.)?• Do you work? How much (hrs/week)?• Any interesting tidbit about who you are thus far?
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PHYS 1302 This is a 3-semester credit hour course
lasting 15 weeks (not 6 weeks).
You should spend 2 hours of prep time out of class for every hour in classclass for every hour in class. Distributed as 45 hours meeting & lecture
90 hours preparation9 hours/week commitment!
Reading assignments, weekly homework assignments, study time.
PHYS1302 syllabusPHYS1302 syllabus WHAT IS A SYLLABUS? It is an outline of the course, the instructor’s policies, and a
schedule of topics, due dates, and exams. Read it thoroughly and keep it as a reference.
MEETING TIMES: Mon. and Wed. 5:00-6:15, MCS #100
FACULTY AND STAFF COMMUNICATIONS:
Instructor: Dr. Grady Price Blount, Vincent Building #175, 942-2526, [email protected]
Staff: Ms. Gayla Trotter, Vincent Building #175, 942-2024, [email protected]
INTRODUCTION: This course is a survey of planetary science. Major topics include the scientific method and the origin and evolution of planetary systems.
STUDENT LEARNING OBJECTIVES: After successful completion of this course you will be able to describe the scientific method as applied to planetary science, list key events in the history and development of human understanding of the solar system, explain current theories on the origin and evolution of planetary systems, and discuss the physical attributes of our planetary neighborhood. You should also be able to appreciate the impact of the Copernican revolution, and modern concepts of the time scales and distance scales of the solar system versus the rest of the universe.
READINGS: The Cosmic Perspective, 4th edition: The Solar System, by Bennett, Donahue, Schneider and Voit, Benjamin Cummings, 2007. 5th edition OK too.
Copies of the lecture slides are available on-line at: www.sci.angelo.edu/phys1302
PHYS1302 syllabusPHYS1302 syllabus
• Demonstration of Proficiency (Grading)• 300 points from four lecture exams at 100 points
each• 3 term exams plus 1 final exam @ 100 points each (lowest score
f )from these 4 is dropped).
• 100 points from in-class quizzes/assignments:
• Percentage curve applied at the end of the semester!
PHYS1302 syllabusPHYS1302 syllabus
• On-Line Assignments• Sign up for class list-serve
• If you’re in lab, PHYS 1102 weekly assignmentsy , y g• www.masteringastronomy.com
• Click on the Solar System edition• Course ID is “fall2009gpb”
• Assignment 1 & 2 due on September 9th
• Other Information on syllabus to read:• Activities, how this course relates to your
education, and general information.
How to attend lecture Show up.Show up.
Classroom decorum:Classroom decorum: No disruptions (you will be asked to leave).No disruptions (you will be asked to leave).
No return if you leave.No return if you leave.
Sit close to front (you’ll hear and see better)Sit close to front (you’ll hear and see better)
Be prepared: read assignments in textbook BEFORE Be prepared: read assignments in textbook BEFORE class class —— make notes of main points, new topics, etc.make notes of main points, new topics, etc.
Take careful notes in your own words. You may Take careful notes in your own words. You may download the lecture slides from the class web site download the lecture slides from the class web site —— but but be aware that the files may change during the week.be aware that the files may change during the week.
After class, review and recopy your notes into a “final” After class, review and recopy your notes into a “final” form.form.
How to complete assignmentsHow to complete assignments
There will be random in-class assignments or quizzes worth 10 X 10 = 100 points.
Show up! Listen carefully Listen carefully. Take notes to remind yourself. Your own work is required. If cheating is
detected, all students turning in questionable work will be assigned a grade of zero for entire quiz or assignment.
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How to preparefor exams
The exams are 60-90% multiple choice or T-F, plus 10-40 point short essay.
Multiple choice questions will be challenging! Multiple choice questions will be challenging!
Don’t wait to the last minute!
Keep developing your notes and challenging yourself with self-tests, on-line tutorials, study groups, writing out possible essays.
Use Mastering Astronomy resources.
How to use onHow to use on--line line resourcesresources
Check the PHYS 1302 web site:Check the PHYS 1302 web site: www.sci.angelo.edu/phys1302www.sci.angelo.edu/phys1302
Sign up for the PHYS1302 listSign up for the PHYS1302 list--serveservegg Read the listRead the list--serve messages!serve messages! Complete the onComplete the on--line tutorials under “Study line tutorials under “Study
Area” and “Tutorials”Area” and “Tutorials” Check Weekly Notes for info on exams, Check Weekly Notes for info on exams,
grades, etc.grades, etc.
Contacting meContacting me
Office is Vincent #175Office is Vincent #175 Office hours are every afternoon.Office hours are every afternoon. Email me: Email me: [email protected]@angelo.edu I usually reply promptlyI usually reply promptly I usually reply promptly. I usually reply promptly. Try to be specific.Try to be specific. Please include your name and contact Please include your name and contact
information so that I can reply!information so that I can reply!
How to use the bookHow to use the book
The Cosmic Perspective, 4The Cosmic Perspective, 4thth Edition: The Edition: The Solar System by Bennett et al., 2007 (or Solar System by Bennett et al., 2007 (or 55thth))
OnOn--line tutorials and Study Area at line tutorials and Study Area at masteringastronomy.com..
Read for comprehension, not completion.Read for comprehension, not completion.
Preface, pages xiii to xx have overview. Preface, pages xiii to xx have overview.
How to Succeed, pages xxvi to xxviiHow to Succeed, pages xxvi to xxvii
Major Themes WovenMajor Themes Woventhroughout the Bookthroughout the Book
Using the text…pages xxvi through xxvii Read the learning goals on first page of each chapter. Study the illustrations and read captions.y p Read the main chapter text for comprehension. Then go back and read the boxed insets
Special Topics and Common Misconceptions
Read the Summary of Key Concepts Test yourself by doing the Exercises and Problems
Study time, study time, study time…
Reminder about signing up Reminder about signing up for PHYS1302 list servefor PHYS1302 list serve
This is your second 10 point inThis is your second 10 point in--class freebee.class freebee.
To subscribe send an email from your account:To subscribe send an email from your account:
[email protected]@angelo.eduSubject: subscribeSubject: subscribe
To send a message to the list:To send a message to the list:
[email protected]@angelo.edu
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ObservationObservation
Up close and personal does not mean accurate
t or correct
Some things can only be understood by integrating knowledge from many sources
Doing science •• Scientists have a logical paradigm (world Scientists have a logical paradigm (world
view)view)
•• Scientists distinguish between truth and Scientists distinguish between truth and factsfactsfactsfacts
•• Scientists parse sentencesScientists parse sentences
•• They are very careful about what they They are very careful about what they say and how they say it (and that means say and how they say it (and that means you have to be very careful listening).you have to be very careful listening).
Parse parse pɑrs, pɑrz/ verb, parsed, pars·ing. –verb (used
with object) 1.to analyze (a sentence) in terms of grammatical constituents, identifying the parts of speech, syntactic relations, etc.
Parsing is a required element of critical thinking. “That depends on what the meaning of “is” is ” That depends on what the meaning of is is… Try these….
“Reliable sources indicate Iraq has weapons of mass destruction”
“Iraq has weapons of mass destructions” “Everything on sale at up to 50% off” “Everything is on sale at 50% off” “This item is not available in all states” “This item is not available in some states”
Primero•• Let’s be clear on a few thingsLet’s be clear on a few things
•• This is a science class so we’re going to use...This is a science class so we’re going to use...
•• the rules of logic to reach reasonable the rules of logic to reach reasonable conclusions.conclusions.
•• When everyone agrees that a reasonable When everyone agrees that a reasonable conclusion has been reached…a Fact arises. conclusion has been reached…a Fact arises.
•• Logical Science seeks Facts, NOT truth.Logical Science seeks Facts, NOT truth.
•• Scientific Truth is an oxymoron.Scientific Truth is an oxymoron.
•• Science does not seek truth. Science does not seek truth.
What is Truth?• (1) the state of being the case (judicial sense),
(2) fundamental reality (spiritual sense), (3) the property of being in accord with REALITY(common usage)• Where REALITY = “of or relating to fixed, permanent,
and unchangeable things”and unchangeable things .• What is your birthdate? Who are your parents? etc.
• The central tenets of Religion and Law are based on truth.
• Science studies a constantly changing universe which exists across 20 orders of magnitude...• Birth and Death of organisms, mountain ranges,
galaxies, stellar life cycles, planetary motions...
• Therefore, Science cannot seek truth*.
Things are made of littler things that jiggle
•• If you think you are living in reality (fixed, If you think you are living in reality (fixed, permanent, unchanging) you are not paying permanent, unchanging) you are not paying attention.attention.
•• “Reality” exists in the “Reality” exists in the world of truth.world of truth.
•• The universe you live in The universe you live in is dynamic (changing).is dynamic (changing).
•• The The physical universephysical universeand and realityreality are two are two different things.different things.
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The Physical Universe•• Is constantly changing on all time scales Is constantly changing on all time scales
and all spatial (space) scales. and all spatial (space) scales.
•• Atomic motion is so fast, all we “see” is Atomic motion is so fast, all we “see” is the averagethe average
•• Is constantly changing on all time scales Is constantly changing on all time scales and all spatial (space) scales. and all spatial (space) scales.
•• Atomic motion is so fast, all we “see” is Atomic motion is so fast, all we “see” is the averagethe averagethe average.the average.
•• Erosion is so slow we don’t live long Erosion is so slow we don’t live long enough to “see” what is happening.enough to “see” what is happening.
•• Galactic motion is so large we cannot see Galactic motion is so large we cannot see what is happening.what is happening.
•• But the good news is…But the good news is…
the average.the average.
•• Erosion is so slow we don’t live long Erosion is so slow we don’t live long enough to “see” what is happening.enough to “see” what is happening.
•• Galactic motion is so large we cannot see Galactic motion is so large we cannot see what is happening.what is happening.
•• But the good news is…But the good news is…
We have facts…•• A fact is A fact is an agreed upon observationan agreed upon observation. .
•• A fact A fact is a reproducible and observable is a reproducible and observable statestate under a given set of conditions.under a given set of conditions.——What is the temperature?What is the temperature?What is the temperature?What is the temperature?
•• A fact is a statement of how the natural A fact is a statement of how the natural world usually responds in a given world usually responds in a given situation. Facts describe change! situation. Facts describe change!
•• Facts are the basis of Natural Laws.Facts are the basis of Natural Laws.
•• By definition, Facts are subject to change.By definition, Facts are subject to change.
Wait a minute…
•• If everything is changing, how do you If everything is changing, how do you know anything?know anything?
•• Scientists do use one very specific Scientists do use one very specific form of truth (the state of being the form of truth (the state of being the case)case)
•• Boolian logic: 2 + 2 = 4, why?Boolian logic: 2 + 2 = 4, why?
•• Because we said so.Because we said so.
LogicLogic Scientists use logic.
Based on the idea of testing premises * State an argument, any argument. Then test it. It can be valid = true, or invalid = false. In mathematics, the argument is “defined”
If A = B and B = C, then A = C Is A = C a fact (an agreed upon observation)? Is A C a fact (an agreed upon observation)? Is A = C true (the state of being the case)? How about A = D?
DEDUCTIVE ARGUMENTS A deductive argument is one in which the conclusion is certain based on the
premises. If the premises are correct then the conclusion is 100% certain.
INDUCTIVE ARGUMENTS An inductive argument is one in which the conclusion is probable based on the
premises. In an inductive argument the conclusion goes beyond the premises.
* a proposition supporting or helping to support a conclusion
I’m a policeman...I’m a policeman... I visit the nearby prison and notice that
all the prisoners on death row have blue eyes.
Here are some testable statements: (Deductive
The observation
or Inductive)?
1 – All of the people on death row have blue eyes.
2 - All of the people convicted of murder have blue eyes.
3 - All murderers have blue eyes.
4 - All people with blue eyes are murderers.
Dec
reas
ing
pre
cisi
on
I’m a scientist...I’m a scientist... I visit the nearby prison and notice that
all the prisoners on death row have blue eyes.
Here are some testable statements: (Deductive or Inductive)?Inductive)?
1 – All of the prisoners on death row in this prison appear to have blue eyes
Only one statement can be agreed upon as a fact
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Some logical rules You must define your criteria.
“Half of the test animals died. The other one lived.”
Normal variance does not negate a conclusion. e.g. the 98 year old smoker
F t t b t t bl f di l Facts must be testable for disproval.
You cannot prove a negative.
Inferences about a group must be supported by evidence representing the entire group. e.g. “All people with blue eyes are murderers”
To disprove a hypothesis you must invalidate a premise which the conclusion depends upon.
100% agreement not necessary to establish a fact.
Order from ChaosOrder from Chaos
The physical universe changes The physical universe changes constantly, but…constantly, but…y,y,
It changes according to rulesIt changes according to rules
We can understand those rulesWe can understand those rules
And predict the futureAnd predict the future
Lab AssignmentsLab Assignments Will be onWill be on--line 2 weeks prior to due date.line 2 weeks prior to due date. Two assignments in first batch.Two assignments in first batch. Get online now. Get online now. Get the book:Get the book:
Read Preface, Chapters 1 & 2Read Preface, Chapters 1 & 2
Do onDo on--line Assignments 1 & 2 by line Assignments 1 & 2 by September 9September 9thth
Getting StartedGetting Started
• www.masteringastronomy.com
• Go through registration screens
Getting StartedGetting Started
• Register with code from card
• Do not share• Do not share codes
• This is how your scores are kept!
masteringastronomy.commasteringastronomy.com
Explore tabs on left side of screen
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masteringastronomy.commasteringastronomy.com
You have two assignments due by September 9th
PHYS 1302PHYS 1302Astronomy of the Solar SystemAstronomy of the Solar System
The scientific study of the space The scientific study of the space environment in our neighborhood.environment in our neighborhood.environment in our neighborhood.environment in our neighborhood. Includes some history, some basic celestial Includes some history, some basic celestial
mechanics, space flight, remote sensing, mechanics, space flight, remote sensing, satellite communications, a little bit of rocketry, satellite communications, a little bit of rocketry, lots of planetary science, some stellar lots of planetary science, some stellar evolution & cosmochemistry, and a little evolution & cosmochemistry, and a little exobiology……. exobiology…….
PHYS 1302Astronomy of the Solar System
Solar System = Everything within the heliopause (the boundary between our Sun and interstellar space).
Space = Everything above 60 miles (100 km) altitude.
Science = The observation, identification, description, experimental investigation, and theoretical explanation of phenomena.
Everything within the heliopause is yours…
Not so long ago…Not so long ago…
The New Solar SystemThe New Solar System
• One thermonuclear object
• Small rocky objects close-in to the middle
• Big gaseous objects farther out
• Millions of small objects
• A halo of comets really far out
Traditional PlanetsTraditional Planets
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What do we mean?What do we mean? When we say “planet” Literally wanderers
Objects that appear to be moving against theObjects that appear to be moving against the fixed background of stars.
Different, therefore, special
Special, therefore, important
A 3,000 year history of sloppy thinking gets another turn at bat…the Pluto thing
Gravitational instabilities in a protostellar nursery collapse towards center.
Heavier elements drawn to
How is a Solar System Created?
Heavier elements drawn to middle - lighter elements to outside.
Localized eddies form the planets.
Leftover debris forms cometary halo.
The Solar System is well-behaved
Almost all of the objects, big and small:
•Same age with a common origin
•Circular Orbits (pretty close anyway)
• All in the same plane
• Spin in the same direction
• Rotate around the Sun in the
same direction
• Obey distance vs. density rule-High Density close in-Lower Density farther out
Terrestrial PlanetsTerrestrial Planets•• Mercury, Venus, Earth Mercury, Venus, Earth
MarsMars-- all made of rockall made of rock
CC•• Close to the sunClose to the sun
•• Relatively smallRelatively small
•• All the same ageAll the same age
•• All made of the same All made of the same stuffstuff-- silicates (quartz, feldspar)silicates (quartz, feldspar)
Gas GiantsGas Giants• Jupiter, Saturn, Uranus, NeptuneJupiter, Saturn, Uranus, Neptune
-all made of gas
-but with rocky cores
Far from the SunFar from the Sun• Far from the SunFar from the Sun
•• Relatively bigRelatively big
•• All the same ageAll the same age
•• All made of gasAll made of gas-mostly Hydrogen and Helium
••All have moons made of ice (lots of moons)All have moons made of ice (lots of moons)
A mini-Solar SystemA mini-Solar System
Ganymede larger than Mercury or Pluto
Io most volcanically Io most volcanically active body in SS
Europa has liquid water ocean beneath frozen crust
Type cases for alternative volcanism Sulfur volcanism Ice volcanism
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What’s missing?
• CometsComets• Asteroids
-Rocky debris between Mars and Jupiter
• Kuiper Belt Objects-Icy planetesimals beyond Pluto
The edge of the unknown…The edge of the unknown…
TitanTitan
Planets?Planets?
Starbirth
Extrasolar Planetary Extrasolar Planetary SystemsSystems
42 Confirmed planets
Most are extremely large (Jupiter-sized or bigger)
or-or-
In large orbits
Most common around sun-like stars
All associated with disk systems
Chapter 1Chapter 1Our Place in the UniverseOur Place in the Universe
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1.1 A Modern View of the 1.1 A Modern View of the UniverseUniverse
•• What is our place in the universe?What is our place in the universe?How did we come to be?How did we come to be?
Our goals for learning:
•• How did we come to be?How did we come to be?•• How can we know what the universe was like in How can we know what the universe was like in
the past?the past? Can we see the entire universe?Can we see the entire universe?
Our place in a BIG universe?Our place in a BIG universe?
A large, glowing ball of gas that generates heat A large, glowing ball of gas that generates heat and light through nuclear fusionand light through nuclear fusion
StarStar PlanetPlanet
A moderately large object that orbits a star; it A moderately large object that orbits a star; it shines by reflected light. Planets may be rocky, shines by reflected light. Planets may be rocky,
icy, or gaseous in composition. icy, or gaseous in composition.
Mars Neptune
Moon (or satellite)Moon (or satellite)
An object that orbits An object that orbits a planet.a planet.
Ganymede (orbits Jupiter)
AsteroidAsteroid
A relatively smallA relatively smallA relatively small A relatively small and rocky object and rocky object that orbits a star.that orbits a star.
Ida
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CometComet
A relatively A relatively small and icy small and icy object that object that orbits a star.orbits a star.
Solar (Star) SystemSolar (Star) System
A star and all A star and all the material the material that orbits it, that orbits it, including its including its planets and planets and moonsmoons
NebulaNebula
An interstellar cloud An interstellar cloud of gas and/or dustof gas and/or dust
GalaxyGalaxyA great island of stars in space, all held A great island of stars in space, all held
together by gravity and orbiting a together by gravity and orbiting a common centercommon center
M31, The Great Galaxyin Andromeda
UniverseUniverse
The sum total of all matter and energy; The sum total of all matter and energy; that is, everything within and between that is, everything within and between
all galaxiesall galaxies
How did we come to be?How did we come to be?
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How can we know what the universe How can we know what the universe was like in the past?was like in the past?
Light travels at a finite speed (300,000 km/s).Light travels at a finite speed (300,000 km/s).
DestinationDestination Light travel timeLight travel time
MoonMoon 1 second1 second
SunSun 8 minutes8 minutes
Thus, we see objects as they were in the past:Thus, we see objects as they were in the past:The farther away we look in distance, The farther away we look in distance,
the further back we look in time.the further back we look in time.
SiriusSirius 8 years8 years
Andromeda GalaxyAndromeda Galaxy 2.5 million years2.5 million years
Example:Example:
We see the Orion We see the Orion Nebula as it Nebula as it looked 1,500 looked 1,500
years ago.years ago.
M31, The Great Galaxyin Andromeda
Example:Example:
This photo shows the Andromeda Galaxy as it looked aboutThis photo shows the Andromeda Galaxy as it looked about2 1/2 million years ago. 2 1/2 million years ago.
Question: When will be able to see what it looks like now?Question: When will be able to see what it looks like now?
M31, The Great Galaxyin Andromeda
LightLight--yearyear
The The distancedistance light can travel in one light can travel in one year.year.
About 10 trillion km (6 trillion miles).About 10 trillion km (6 trillion miles).
•• At great distances, we see objects as they wereAt great distances, we see objects as they were
when the universe was much younger.when the universe was much younger. What have we learned?What have we learned?
What is our physical place in the universe?What is our physical place in the universe? Earth is part of the Solar System, which is the Earth is part of the Solar System, which is the
Milky Way galaxy, which is a member of the Milky Way galaxy, which is a member of the Local Group of galaxies in the Local Local Group of galaxies in the Local SuperclusterSuperclusterSuperclusterSupercluster
How did we come to be?How did we come to be? The matter in our bodies came from the Big The matter in our bodies came from the Big
Bang, which produced hydrogen and heliumBang, which produced hydrogen and helium All other elements were constructed from H and All other elements were constructed from H and
He in star and then recycled into new star He in star and then recycled into new star systems, including our solar systemsystems, including our solar system
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What have we learned?What have we learned?
How can we know that the universe How can we know that the universe was like in the past?was like in the past? When we look to great distances we are When we look to great distances we are
seeing events that happened long agoseeing events that happened long agoseeing events that happened long ago seeing events that happened long ago because light travels at a finite speedbecause light travels at a finite speed
Can we see the entire universe?Can we see the entire universe? No, the observable portion of the universe No, the observable portion of the universe
is about 14 billion lightis about 14 billion light--years in radius years in radius because the universe is about 14 billion because the universe is about 14 billion years oldyears old
1.2 The Scale of the Universe1.2 The Scale of the Universe
•• How big is Earth compared to our solar How big is Earth compared to our solar system?system?
Our goals for learning:
system?system?•• How far away are the stars?How far away are the stars?•• How big is the Milky Way Galaxy?How big is the Milky Way Galaxy?•• How big is the universe?How big is the universe?•• How do our lifetimes compare to the age How do our lifetimes compare to the age
of the universe?of the universe?
How big is Earth compared to our solar How big is Earth compared to our solar system?system?
Let’s reduce the size of the solar system by a Let’s reduce the size of the solar system by a factor of 10 billion; the Sun is now the size of a factor of 10 billion; the Sun is now the size of a
large grapefruit (14 cm diameter).large grapefruit (14 cm diameter).
How big is Earth on this scale?How big is Earth on this scale?
A.A. an atoman atom
B.B. a ball pointa ball point
C.C. a marblea marble
D.D. a golf balla golf ball
How far away are the stars?How far away are the stars?
How far would you have to walk to reach Alpha How far would you have to walk to reach Alpha Centauri?Centauri?
AA 1 mile1 mileA.A. 1 mile1 mile
B.B. 10 miles10 miles
C.C. 100 miles100 miles
D.D. the distance across the U.S. (2500 the distance across the U.S. (2500 miles)miles)
How do our lifetimes compare to the How do our lifetimes compare to the age of the Universe?age of the Universe?
The Cosmic Calendar: a scale on which we The Cosmic Calendar: a scale on which we compress the history of the universe into 1 compress the history of the universe into 1 year. year.
1.3 Spaceship Earth1.3 Spaceship Earth
•• How is Earth moving in our solar system?How is Earth moving in our solar system?
•• How is our solar system moving in the How is our solar system moving in the
Our goals for learning:
Galaxy?Galaxy?
•• How do galaxies move within the How do galaxies move within the Universe?Universe?
•• Are we ever sitting still?Are we ever sitting still?
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How is Earth moving in our solar system?How is Earth moving in our solar system?
Contrary to our perception, we are not “sitting still.”Contrary to our perception, we are not “sitting still.”
We are moving with the Earth in several ways, and at We are moving with the Earth in several ways, and at surprisingly fast speeds…surprisingly fast speeds…
The Earth rotatesThe Earth rotatesaround its axis once every day.
Earth orbits the Sun (revolves) once every year:Earth orbits the Sun (revolves) once every year:Earth orbits the Sun (revolves) once every year:Earth orbits the Sun (revolves) once every year:
• at an average distance of 1 AU ≈ 150 million km.• with Earth’s axis tilted by 23.5º (pointing to Polaris)• and rotating in the same direction it orbits, counter-
clockwise as viewed from above the North Pole.
C = pi X 2r Orbital velocity = C / 365.25 days
Our Sun moves randomly relative to the other stars in Our Sun moves randomly relative to the other stars in the local Solar neighborhood…the local Solar neighborhood…• typical relative speeds of more than 70,000 km/hr• but stars are so far away that we cannot easily noticetheir motion
… And orbits the galaxy every 230 million years.
Are we ever sitting still?Are we ever sitting still?Earth rotates on axis: > 1,000 km/hr
Earth orbits Sun: > 100,000 km/hr
Solar system moves among stars: ~ 70,000 km/hr
Milky Way rotates: ~ 800,000 km/hry y ,
Milky Way moves in Local Group
Universeexpands
1.4 The Human Adventure of 1.4 The Human Adventure of AstronomyAstronomy
•• How has the study of astronomy How has the study of astronomy affected human history?affected human history?
Our goals for learning:
affected human history?affected human history?
How has the study of astronomy How has the study of astronomy affected human history?affected human history?
Copernican Revolution showed that Earth was not the Copernican Revolution showed that Earth was not the center of the universe (Chapter 3)center of the universe (Chapter 3)
Study of planetary motion led to Newton’s Laws of Study of planetary motion led to Newton’s Laws of motion and gravity (Chapter 4)motion and gravity (Chapter 4)motion and gravity (Chapter 4)motion and gravity (Chapter 4)
Newton’s laws laid the foundation of the industrial Newton’s laws laid the foundation of the industrial revolutionrevolution
Modern discoveries are continuing to expand our Modern discoveries are continuing to expand our “cosmic perspective”“cosmic perspective”
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A new view of “home”A new view of “home”
