Astronomy%20100%20Tuesday,%20Thursday%202:30%20-%203:[e-mail]

1
Astronomy 100Tuesday, Thursday 230 - 345
pmTom Burbinetburbine_at_mtholyoke.edu
2
(No Transcript)
3
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.

4
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

5
Course is divided into 4 Sections

• The Night Sky
• Gravity, Light, and Spacetime
• The Nature of Stars
• Galaxies and the Universe

6
Star Trek

• Antimatter
• Faster than Light Travel
• Alien Races

7
Battlestar Galactica

• Interstellar Travel

8
Theme

• Does life exist elsewhere in the solar system?
• Does life exist elsewhere in the Universe?

9
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

10
Grades

• 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

11
Exams

• 1 Feb 15 Tuesday
• 2 March 10 Thursday
• 3April 7 Thursday
• 4 May 10 Tuesday
• Final May 14-20

12
Makeup Exams

• If you miss an exam, I need a doctors 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

13
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

14
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!!

15
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

16
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

17
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

18
Now some Astronomy

• The first thing we will talk about is distance
• The huge distances that occur in the universe

19
(No Transcript)
20
Things you need to know because we will use the
metric system

• 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?

21
(No Transcript)
22
5,900 million km 5,900,000 million meters
590 meters
The distances are one ten-billionth of their
actual values
23
(No Transcript)
24
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?

25
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)

26
(No Transcript)
27
Scientific Notation

• 10000 104
• 100000000 108
• 10000000000 1010
• 100000000000000000000 1020
• 0.001 10-3
• 0.0000001 10-7

28
How do you write numbers?

• 31700000 3.17 x 107
• 2770000 2.77 x 106
• 0.00056 5.6 x 10-4
• 0.0000078 7.8 x 10-6

29
How do you do multiply?

• 106 x 108 10(68) 1014
• 10-5 x 103 10(-53) 10-2
• (3 x 104 ) x (4 x 105) 12 x 10(45) 12 x 109
  1.2 x 1010

30
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

31
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

32
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

33
When we are looking at stars or galaxies

• We are looking into the past

34
Milky Way Galaxy

• Milky Way is 100,000 light years in diameter
• There are 100 billion stars in the Milky Way

35
Stars in the Universe

• Say there are 100 billion galaxies
• Each galaxy has 100 billion stars
• So how many stars in the universe

36
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

37
Time
38
Spaceship Earth

• We are travelling through the Universe
• Velocity distance/time

39
Earth is rotating

• The Earth is rotating counterclockwise looking
  down the north pole
• This is why the Sun rises in the East

40
We are rotating around the Sun
41
Stars near us are also moving

• Average relative velocities of nearby stars
  is 70,000 km/hr

42
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
43
Stars in the Milky Way are rotating

• The sun is rotating around the galactic center
  at 800,000 km/hr

44
The Universe is also expanding
Galaxies (outside the Local Group) that are
farther away from us appear to be moving faster