Expanding Universe ?

Universe [n. YOU-nee-verse]
The Universe is the whole body of things in the cosmos, including all the stars and planets. It is also used to mean the world of human experience here on earth. Universe comes from the Latin universum which comprises unus (one) and versum (to turn). It means to turn into one, combine into a whole, and was introduced in English in the 16th century.

Astronomers see countless galaxies for billions of light years in every direction. The farther away a galaxy is, the faster it moves away from us. The whole universe is expanding. How do we know?

When an object moves away from an observer, the light from that object changes color, similar to the way a train whistle changes pitch if the train is moving away. This "Doppler shift" causes the light of receding galaxies to stretch out, becoming more reddish. Measuring this "red shift," astronomers can tell how fast each galaxy is receding.

If the universe is currently expanding, it makes sense that at one time it was much smaller. The "Big Bang" theory, which describes how the universe might have started in a stupendous explosion, is one possible explanation of how the universe began.

The Hubble Constant is a number for how fast the universe is expanding:
http://csep1.phy.ornl.gov/guidry/violence/hubble_constant.html

How big is the universe?
http://features.LearningKingdom.com/fact/archive/1998/11/02.html

More evidence for the Big Bang theory:
http://features.LearningKingdom.com/fact/archive/1998/09/11.html

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