Astronomy 100 Tuesday, Thursday 2:30 - 3:45 pm Tom Burbine

Course Material Course Website: 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 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 You get some type of A You get some type of B You get some type of C You get some type of D If the average is not reasonable, I will curve up

Exams #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

1 st 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 2 nd 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 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?

590 meters 5,900 million km = 5,900,000 million 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 = = = = = = 10 -7

How do you write numbers? = 3.17 x = 2.77 x = 5.6 x = 7.8 x 10 -6

How do you do multiply? 10 6 x 10 8 = 10 (6+8) = x 10 3 = 10 (-5+3) = (3 x 10 4 ) x (4 x 10 5 ) = 12 x 10 (4+5) = 12 x 10 9 = 1.2 x 10 10

How do you divide? 10 8 /10 6 = 10 (8-6) = /10 -4 = 10 (-6-(-4)) = (3 x 10 8 )/(4 x 10 3 ) = ¾ x 10 (8-3) = 0.75 x 10 5 = 7.5 x 10 4

Terms for large distances In the Solar System astronomical unit (AU) = distance between Earth and Sun (1.5 x 10 8 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 10 8 m/s) x (1 yr) x (365 days/yr) x (24 hr/day) x (60 min/hr) x (60 s/min) = 9.46 x 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 10 9 ) x (100 x 10 9 ) = x = 1 x 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 You are here Long wavelength 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