Download Linking Asteroids and Meteorites through Reflectance

Astronomy 100
Tuesday, Thursday 2:30 - 3:45 pm
Tom Burbine
[email protected]
Course Material
• Course Website: www.xanga.com/astronomy100
• Textbook: Stars, Galaxies, and Cosmology, The
Cosmic Perspective, 3rd Edition by Bennett,
Donahue, Schneider, and Voit
• PRS: You need to have an InterWrite PRS
transmitter.
Goals of the Class for Me
• The class should be interesting
• You should learn some fundamental concepts in
Astronomy
• Motivate a few people to be Astronomy majors
Course is divided into 4 Sections
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The Night Sky
Gravity, Light, and Spacetime
The Nature of Stars
Galaxies and the Universe
Star Trek
• Antimatter
• Faster than Light Travel
• Alien Races
Battlestar Galactica
• Interstellar Travel
Theme
• Does life exist elsewhere in the solar system?
• Does life exist elsewhere in the Universe?
Grading
• 4 in-class exams and a cumulative final
• I will drop the lowest test score
• The average of the 4 highest scores will be 80%
of your grade
• 10% of your grade will be your homework score
• 10% of your grade will be from PRS
Grades
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90-100 You get some type of A
80-90 You get some type of B
70-80 You get some type of C
60-70 You get some type of D
If the average is not reasonable, I will curve up
Exams
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#1 Feb 15 Tuesday
#2 March 10 Thursday
# 3April 7 Thursday
#4 May 10 Tuesday
Final May 14-20
Makeup Exams
• If you miss an exam, I need a doctor’s excuse or
documented family emergency to give a makeup
exam
• If you are going to miss an exam for a religious
observance or university-sponsored activity, I
need to be contacted in advance
• I will be very strict since I am dropping one exam
Homework
• You need to get a maximum of 20 homework
points out of ~30 possible points
• If you get 20 points, you get 100% homework
score
• I will divide your homework score by 20 to
calculate your percentage with a maximum total
of 100%
• Primarily the assignments will be on OWL
1st HW assignment
• You need to find an article on astronomy (web, newspaper,
magazine)
• Print it, copy it, or cut it out
• Read it
• Write one paragraph on why it is important or why you found
it interesting
• Staple them together
• Write your name and ID number on front page
• Write the first three letters of your last name in big letters on
front page
• Hand it in during next class
• You will then get 1 Homework credit!!
PRS
• 10% of your grade will be from using PRS
• You need to get a maximum of 20 PRS points out
of ~30 possible points
• I will divide your PRS score by 20 to calculate
your percentage with a maximum total of 100%
Student Contract
• I need you to turn it in by the 2nd class
• If I do not get it, I will assume you have dropped
the class
If you are not enrolled in the class and
want to be
• Talk to me afterwards
• I will try to get everybody in the class who wants
to be in it
Now some Astronomy
• The first thing we will talk about is distance
• The huge distances that occur in the universe
Things you need to know because we will
use the metric system
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one kilometer is 5/8 of a mile
one kilometer is 1000 meters
one meter is approximately a yard or 3 feet
We will use the metric system in this class
Do you all remember the Mars Climate Orbiter?
5,900 million km = 5,900,000 million meters
590 meters
The distances are one ten-billionth of their actual values
So how far have we travelled?
• What is the only planetary body that humans have
walked on?
• How many planets have spacecraft visited?
• What spacecraft has travelled the farthest from Earth?
• How far away is the closest star system?
So how far have we travelled?
• What is the only planetary body that humans have
walked on?
• Moon (385,000 km away)
• How many planets have spacecraft visited?
• All planets except Pluto
• What spacecraft has travelled the farthest from Earth?
• Voyager 1 (14 billion km away)
• How far away is the closest star system?
• ~40 trillion kilometers away (Alpha Centauri)
Scientific Notation
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10000 = 104
100000000 = 108
10000000000 = 1010
100000000000000000000 = 1020
0.001 = 10-3
0.0000001 = 10-7
How do you write numbers?
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31700000 = 3.17 x 107
2770000 = 2.77 x 106
0.00056 = 5.6 x 10-4
0.0000078 = 7.8 x 10-6
How do you do multiply?
• 106 x 108 = 10(6+8) = 1014
• 10-5 x 103 = 10(-5+3) = 10-2
• (3 x 104 ) x (4 x 105) = 12 x 10(4+5) = 12 x 109
= 1.2 x 1010
How do you divide?
• 108/106 = 10(8-6) = 102
• 10-6/10-4 = 10(-6-(-4)) = 10-2
• (3 x 108)/(4 x 103) = ¾ x 10(8-3) = 0.75 x 105
= 7.5 x 104
Terms for large distances
• In the Solar System
• astronomical unit (AU) = distance between Earth
and Sun (1.5 x 108 km)
• Mercury is at 0.4 AU from the Sun
• Jupiter is at 5.2 AU from the Sun
Light Year
• A light year is the distance light travels in a year
• The speed of light is the fastest anything can
travel in the universe
• How far is a light year:
(3 x 108 m/s) x (1 yr) x (365 days/yr) x (24 hr/day) x (60 min/hr) x
(60 s/min) = 9.46 x 1015 m
• Alpha Centauri is 4.4 light years away from Earth
When we are looking at stars or galaxies
• We are looking into the past
Milky Way Galaxy
• Milky Way is 100,000 light years in diameter
• There are ~100 billion stars in the Milky Way
Stars in the Universe
• Say there are 100 billion galaxies
• Each galaxy has 100 billion stars
• So how many stars in the universe
Answer
• Number of stars in universe
• = (100 x 109) x (100 x 109) = 10000 x 1018
= 1 x 1022
• This is about the same number of grains of sand
in every beach in the world
Time
Spaceship Earth
• We are travelling through the Universe
• Velocity = distance/time
Earth is rotating
• The Earth is rotating
counterclockwise looking
down the north pole
• This is why the Sun rises
in the East
We are rotating around the Sun
Stars near us are also moving
• Average relative
velocities of nearby
stars is
70,000 km/hr
Doppler Shift
Long wavelength
You are
here
Short wavelength
We can measure how spectral features at known wavelengths
Change wavelength positions and determine how fast a star or galaxy
is moving away from us
Stars in the Milky Way are rotating
• The sun is rotating
around the galactic center
at 800,000 km/hr
The Universe is also expanding
Galaxies (outside the Local Group) that are farther away
from us appear to be moving faster