Transcript ISP 205: Visions of the Universe

Welcome to
Astronomy!
Introduction
to
the Universe
Astro 1105/1107
Prof. Julia Kregenow
Star
A large, glowing ball of gas that generates heat
and light through nuclear fusion
Galaxy
A great island of stars in space, all held
together by gravity and orbiting a
common center
M31, The Great Galaxy
in Andromeda
Universe
The sum total of all matter and energy;
that is, everything within and between
all galaxies
Your Goals: Brief Survey
What do you want to learn about astronomy?
Write down a few things.
My Goals: on Syllabus
On course website:
www.astro.cornell.edu/academics/courses/astro105/
Please read it carefully!
Homework for TOMORROW
• Read Syllabus online -- quiz tomorrow!
– The syllabus is our CONTRACT
• Register on “MasteringAstronomy” website
– Instructions on our course webpage
www.astro.cornell.edu/academics/courses/astro105/
– Enroll in our course: (ID# given on syllabus)
• First online assignment due tomorrow 10:30am
– “Introduction to MasteringAstronomy” (see HW page)
SOME REALLY BIG IDEAS
Science
Light
Lookback time
Gravity
Star stuff
Expanding universe
Space is big. And empty.
Chapter 1
Our Place in the Universe
How did we come to be?
Pg. 4
The Universe is Dynamic
Everything is moving
Some terminology:
Expansion
Revolve vs. Rotate
What motion does the Earth undergo?
What motion does the Sun undergo?
There are over 100,000,000,000 stars in our galaxy.
?
?
Thought Question
Suppose you tried to count the more than 100 billion
stars in our galaxy, at a rate of one per second…
How long would it take you?
Unit Conversion
Convert 100 Billion seconds to years
Seconds -> Minutes -> Hours -> Days -> Years
Lookback Time
• We see objects as they were in the past:
• Light travels at a finite speed (300,000 km/s).
• The farther away we look in distance, the further
back we look in time.
• Allows us to study the history of the Universe.
Example: Our nearest neighbor.
This photo shows the Andromeda Galaxy as it looked about
2 1/2 million years ago.
Question: When will be able to see what it looks like now?
Fig. 1.4
M31, The Great Galaxy
in Andromeda
Light-year: the distance light travels
in one year.
(But how far is that?)
Math Skills Summary
• Scientific Notation
• Multiply and Divide powers of 10
• Convert Units
• Rearrange an equation to solve for another variable
• Plug numbers in for variables in an equation and calculate
Math Skills Summary
• Scientific Notation
– e.g. 300,000,000 = ?
– e.g. 4x10-5 = ?
• Multiply and Divide powers of 10
– e.g. 108 / 10-5 = ?
• Convert Units
– e.g. How many inches in a mile?
• Rearrange an equation to solve for another variable
– e.g. b = L / 4d2.
Solve for d.
• Plug numbers in for variables in an equation and calculate
– e.g. L = 3.8x1026 watts, d = 1.5x1011 m, b = ?
(show coolpics.ppt)