How big, how old, and how dense is the Universe?

	An exploration by Jeff Vogtschaller University of Wisconsin, Madison

How do astronomers know how far away all those exotic stars and galaxies are, how can they tell there are planets around other stars, and how do we know the universe is expanding? The answer to these questions is all the same!

The Nature of Light

The Doppler Shift

Wobble Stars

Truth in Advertizing

Things that go BANG! in the night

Bailey's Beads

Warm Fuzzy Glow

Let me introduce you to...

A long time ago in a galaxy far, far away

More Things that go BANG! in the night

Dark Matter (or, May the Force be with you!)

The 74% Solution (Dark Energy)

Dark and a Dot Where It's Not

Gravity is Really Weak?

Unknowable?

Planets

Best Bang Since the Big One and Quark Stars

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Image Credits:
Whirlpool galaxy from the Hubble Space Telescope
Yellow flame from PrintShop 20
Colorful CD from PrintShop 20
Multitude of colors from PrintShop 20
Continuous spectrum from Nick Strobel's Astronomy Notes. Visit his site at www.astronomynotes.com
emission-absorption spectrum from Nick Strobel's Astronomy Notes. Visit his site at www.astronomynotes.com
Doppler diagram from www.astronomes.com
Electromagnetic spectrum by NASA/JPL-Caltech;
Wobbling star from +plus Magazine
center of mass & sodium spectra by Deborah Scherrer, Stanford Solar Center
Hubble Deep Field image from HST, NASA
Solar eclipse image from NASA at There Goes the Sun
Cobe-max image from Nobel Prize in Physics for Confirming the Big Bang
Einstein photograph by Oren J. Turner (1947)
Dark matter images from NCAR's Windows to the Universe
Dark energy "pie" from NASA's Chandra website at More images...
Eclipse image of Saturn from NASA, Cassini mission. See In the Shadow of Saturn