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
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Homework (10%)
Projects (2 @ 15%)
Midterm tests (4 @ 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)…
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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:
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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 drivethrough 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…
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Across earth: 0.04 seconds
From moon: 1.3 seconds
From sun: 8 minutes
From Neptune: 4 hours
Light travel times…
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From nearest star: 4 years
From galactic center: 25,000 years
From Andromeda galaxy: 2 million years
From hot early universe: 14 billion years