Introduction to Astronomy Dr. Daniel Schroeder Fall 2006

Today: Course policies and goals A quick tour of the universe

What’s this course about? A tour of the universe: planets, stars, galaxies For anyone who’s curious! Satisfies physical science gen ed No college-level prerequisites

What you’re graded on Homework (10%) Projects 15%) Midterm tests 10%) Comprehensive final (20%) Class participation in borderline cases (Please read syllabus for other policies)

To get the most out of this course (and a decent grade)… Come to class Do all the homework and projects Don’t procrastinate Read with a pencil Ask questions

Will this course be hard? Here’s an analogy…

Advantages of driving: Quicker Less effort Don’t need to be physically fit

Advantages of walking: See a lot more Exercise feels good When you succeed, the mountain is “yours” You get more credit

Think of this course as a guided hike, not a drive- through tour. Reasoning is more important than memorization. It’s not just what we know, but also how we know it.

Necessary equipment Reading Writing Arithmetic

Will the math be too hard? High-school level arithmetic, algebra, geometry We’ll review the obscure stuff. Attitude is more important than ability. If you’ve placed into “developmental math”, you might want to postpone this course.

And now… The view from the summit

Monte Python’s “Global View” Just remember that you're standing on a planet that's evolving And revolving at 900 miles an hour, That's orbiting at 19 miles a second, so it's reckoned A sun that is the source of all our power. The sun and you and me and all the stars that we can see Are moving at a million miles a day In an outer spiral arm, at 40,000 miles an hour Of the galaxy we call the Milky Way. Our galaxy itself contains 100 billion stars It's 100,000 light years side to side. It bulges in the middle, 16,000 light years thick But out by us it's just 3,000 light years wide We're 30,000 light years from galactic central point, We go round every 200 million years And our galaxy is only one of millions of billions In this amazing and expanding Universe. The Universe itself keeps on expanding and expanding In all of the directions it can whizz As fast as it can go, at the speed of light you know, 12 million miles a minute, and that's the fastest speed there is So remember when you're feeling very small and insecure How amazingly unlikely is your birth And pray that there's intelligent life somewhere up in space Because there's bugger all down here on earth.

Special offer! Find and document the inconsistency in the numbers in the song, and win a free Milky Way bar! (Fine print: Documentation must be in writing. You may use outside sources for clues, but the challenge is to find an inconsistency within the song itself. The error is significant--not merely a matter of rounding off.)

Light travel times… Across earth: 0.04 seconds From moon: 1.3 seconds From sun: 8 minutes From Neptune: 4 hours

Light travel times… From nearest star: 4 years From galactic center: 25,000 years From Andromeda galaxy: 2 million years From hot early universe: 14 billion years