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Charles HakesFort Lewis College 3
Outline
Logistics Review clicker checkup The view from Earth Some General Science background
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Class Introduction
• Class Web Site is: http://faculty.fortlewis.edu/hakes_c/
• Also you will need: http://www.masteringastronomy.com
• ASTRONOMYHAKESF11
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Logistics
• Homework Study sessions…• (Looking for tutor)• Login Issues?
• Manila Folder format - today, write your full name on the tab, and large “call name” on the front.
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Class Objective
• To gain a general understanding of the contents of your universe and how it works.
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Class Objective
• To gain a general understanding of the contents of your universe and how it works.
• To learn about some of the physical laws that control the universe.
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Class Objective
• To gain a general understanding of the contents of your universe and how it works.
• To learn about some of the physical laws that control the universe.
• To gain an understanding of the size and age of the universe and the various components.
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Class Objective
• To gain a general understanding of the contents of your universe and how it works.
• To learn about some of the physical laws that control the universe.
• To gain an understanding of the size and age of the universe and the various components.
• To learn how we know what we know. (this is where the “technology” of the course comes in)
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Class Objective
• To gain a general understanding of the contents of your universe and how it works.
• To learn about some of the physical laws that control the universe.
• To gain an understanding of the size and age of the universe and the various components.
• To learn how we know what we know. (this is where the “technology” of the course comes in)
• The content of this course is really more like astrophysics, and it will involve some standard scientific skills, like interpreting plots and performing numerical calculation.
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Class Non-Objective
• This is not a course about horoscopes (astrology) or about stories associated with the constellations (mythology).
• To fulfill an easy distribution requirement. Many students at colleges across the country sign up for astronomy because they think it will be easy (they are usually wrong).
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Teaching Philosophy
• You are the primary person responsible for learning the material. I am a facilitator.
• What you can do.• Read the book. (It is a good one.)• Do the exercises. (They can be challenging.)• Come to class. (Participate!)
• Ask questions.• Discuss questions with your peers.• You will learn the material the best if you can explain it to
someone.
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Teaching Philosophy
• So…• You read the book. (It is a good one.)• You do the exercises. (They can be
challenging.)• You discuss questions with your peers…
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I>clicker Response System
• Add your number to the class roster as you see your name.
• Practice questions will begin now.
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Clicker Practice
What is your favorite color?
A. red
B. yellow
C. green
D. blue
E. purple
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Clicker Practice
How many days will you miss class this semester?
(Enter a number 1-5)
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About how many stars can you see at one time from Durango with your naked eye?
A) 800
B) 4000
C) 20,000
D) 100,000
E) 1,000,000
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About how many constellations can you see at one time?
A) 22
B) 44
C) 88
D) 144
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Magnitude
• Historical Magnitude Scale• Hipparcos/Ptolemy• The brightest stars were “of the first magnitude”• Dimmer stars were second, third, etc.
magnitude.• Dimmest stars were 6th magnitude
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How many Stars Can You See?
Magnitude Range Cumulative Stars % Increase Seen-1 -1.50 to -0.51 2 -
0 -0.50 to +0.49 8 400%
1 +0.50 to +1.49 22 275%
2 +1.50 to +2.49 93 423%
3 +2.50 to +3.49 283 304%
4 +3.50 to +4.49 893 316%
5 +4.50 to +5.49 2,822 316%
6 +5.50 to +6.49 8,768 311%
7 +6.50 to +7.49 26,533 303%
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Constellations
• There are 88 constellations defined on the celestial sphere.
• Many are historical• There are no “empty” places• Many correspond to asterisms.
• Asterism - a noticeable pattern of stars that makes up part of one or more constellations; not a constellation itself.
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Constellations
• The stars in a constellation are not physically close to each other - they just happen to be in the same direction.
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Measurements and Units
http://faculty.fortlewis.edu/hakes%5Fc/
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Measurements
• Measurements allow us to compute quantities and solve problems
• Science attempts to describe nature in an objective way through measurements
• Standard Unit (everyone can understand)• System of Units (group of standards)
• Metric System (SI)• British System
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Mass
• Mass is the only fundamental unit that is still defined by an artifact - a one kg platinum cylinder.
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SI Units
Name of
Unit
Abbreviation Property
Measured
meter m length
kilogram kg mass
second s time
ampere A electric current
kelvin K temperature
mole mol substance amount
candela cd luminous intensity
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Dimensional Analysis
• Dimensional Analysis is VERY helpful in problem solving.
• Check your equations with specific units.• Velocity example - how do distance (x),
time (t), and Velocity (V) relate?
V = x/t
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Velocity Exercise
• You drive 60 miles to Pagosa Springs at 55 miles per hour. How many hours does this take?
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Dimensional Analysis Example - Which equation is correct?
A) velocity = distance * time
B) time = velocity * distance
C) time = distance / velocity
D) time = velocity / distance
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Which equation is correct?
A) velocity = distance * time
B) time = velocity * distance
C) time = distance / velocity
D) time = velocity / distance
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Velocity Exercise
• The laser travels 9.6m across the room. How many seconds does it take?
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Light Travel Time Across the Room (9.6 meters)
A) 2.9x106 sec
B) 2.9x10-6 sec
C) 3.2x10-5 sec
D) 3.2x10-8 sec
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Light Travel Time Across the Room (9.6 meters)
A) 2.9x106 sec
B) 2.9x10-6 sec
C) 3.2x10-5 sec
D) 3.2x10-8 sec