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Galaxies & the Universe - Study Guide

Milky Way

What does our Milky Way galaxy look like?
What kind of galaxy is our Milky Way?
What aspects of the Milky Way's appearance tell us where we are in it?
How do we tell how big the Milky Way is?
What are the structural components of our galaxy?
What are the ingredients for ongoing star formation?
Where is the ongoing star formation in the Milky Way?
How do stars & gas recycle in the Milky Way?
What are orbits of stars like in the disk, bulge and halo of our galaxy?
How do the ages of galactic and globular clusters compare?
How do the stars in the disk differ from those in the spheroidal components (bulge and halo)?
Where are the globular clusters in our Milky Way galaxy?
How old are the globular clusters in our galaxy?
What color are spiral bulges compared to spiral disks and what does that tell us about ongoing star formation?
How old is the bulge of our galaxy relative to the disk of our galaxy?
What aspects of our Milky Way galaxy tell us how it was formed?
How do we weigh spiral galaxies?
How long does it take our solar system to go around our galaxy once?
How do we know dark matter exists in our spiral galaxies?
What is dark matter?

Galaxies

What are the two kinds of spiral arms?
Why are density wave spiral arms so narrow?
What are the major types of galaxies? How are they structured?
What kind of galaxies is most numerous?
Where is the dark matter in spiral galaxies (relative to visible matter)?
How much mass is there in dark matter in galaxies compared to normal matter?
How do we determine the distances to galaxies?
What are two ways that elliptical galaxies can be formed?
When two spiral galaxies collide, do any stars collide? Does their gas interact?
How do we weigh elliptical galaxies?
Why is the gas in elliptical galaxies so hot?
What types of galaxies have the most star formation?
What types of galaxies have the least star formation?
What are "active galactic nuclei" and what is their power source?
What are quasars?
How has nuclear galactic activity evolved over time?

Galaxy Clusters

Why do galaxies gather in clusters?
If the Universe is expanding, how can galaxies cluster?
How are galaxy clusters structured and how do we know they contain dark matter?
What component of galaxy clusters contains the most mass?
Why is the gas in galaxy clusters so hot?
How did the hot gas that permeates galaxy clusters get enriched with heavy elements?
What are the largest gravitational structures in the Universe?
What are three ways with which galaxy clusters can be weighed accurately?

Universe

What is the most important physical fact that allows us to determine how the Universe has evolved?
Why is the sky dark at night? What does this tell us about the Universe?
What kind of Universe do we live in?
When we look at the most distant galaxies, how old do they appear to be?
How did our Universe form?
What observational fact led to the prediction of a Big Bang?
What is the Hubble law?
What does the Hubble Law tell us about the age of our Universe?
How old is our Universe?
Are all galaxies moving away from us?
Is there a center to the expansion of the Universe?
How has the Big Bang model been tested?
What elements were predicted to be created in the early Universe?
What "standard candle" recently allowed astronomers to discover that the Universe is accelerating its expansion?
What is causing the expansion of the Universe to accelerate?
What provides most of the mass/energy content of the Universe?
What is Dark Energy?
How does the abundance of deuterium tell us about what dark matter is (or is not) made of?
How was the Big Bang radiation (Cosmic Microwave Background Radiation) created?
What is the current temperature of the Big Bang radiation?
What was the temperature of matter and radiation at the time the Big Band radiation was emitted?
Why is the Big Bang radiation now 1000 times cooler than when emitted?
How does the Big Bang radiation allow us to measure absolute motion?
Why was the Big Bang radiation predicted to be slightly lumpy?
What are some problems with the simplest form of the Big Bang and
how has the Big Bang model been modified to take care of these problems?

Life in the Universe

Is there life elsewhere in the Universe?
How long does the Solar System take to orbit the galaxy?
How long have humans been technological?
How long has there been life on Earth?
Have we been visited by aliens?

revised 2 Jan 2008