ASTR Spring 2008 Joel E. Tohline, Alumni Professor 247 Nicholson Hall

WELCOME TO ASTRONOMY The required textbook for this course is Universe Eighth Edition by Roger A. Freedman and William J. Kaufmann III (©2007, W.H. Freeman & Company)

UNIVERSE EBOOK An ALTERNATE version of the textbook is available at a lower cost in eBook form! It includes… The complete textbook – every word, graphic, table, and problem. The ability to take notes, highlight, and print. Resources such as animations, simulations, and practice tests. Convenient access to your textbook from any Internet connection – no more carrying around those heavy books!

If your textbook was packaged with an eBook access code, you can redeem it at the site: 1.Click “register.” 2.Fill out the information and you’re ready to go. * Be sure to hold on to the access card until you redeem it. UNIVERSE EBOOK

If you would like to purchase the access, you can do so at the site: 1.Click “purchase.” 2.Enter your school Zip code 3.Choose a user name and password. Fill out the remaining info and you’re ready to go. * Be sure to remember your username and password UNIVERSE EBOOK

Light-Travel Times Speed of light, c = 3 x 10 8 meters/second Travel around the Earth –Circumference of the Earth =  D  = 3.14 x (1.28 x 10 7 m) † = 4.02 x 10 7 meters –Time of travel = distance/speed = (4.02 x 10 7 m)/(3 x 10 8 m/s) = seconds Travel from Earth to Moon –Earth-Moon distance = 3.84 x 10 8 meters ‡ –Time of travel = distance/speed = (3.84 x 10 8 m)/(3 x 10 8 m/s) = 1.3 seconds † Textbook Appendix 2 ‡ Textbook Appendix 3

Light-Travel Times Sun-to-Earth = 8 minutes Across the Radius of the Sun = 2 seconds Earth-to-Saturn = 80 minutes Sun-to-Neptune (edge of solar system) = 4 hrs Sun-to-Proxima Centauri (nearest neighbor star) = 4.4 years Across the diameter of our Milky Way Galaxy = 100,000 years From the Andromeda Galaxy (nearest major neighbor galaxy) to us = 2.5 million years!