2. Red Shift
*The stretching of wavelengths as objects move away from each other.
*Light waves shifting toward longer wavelengths
*Means the object is moving away from us
*Used as evidence that the Universe is expanding

3. Big Bang, Age of the Universe and Evidence
Universe started out the size of a period.
Massive expansion began between 15 and 20 billion years ago.
All galaxies are moving away from us and each other. This is called continuous expansion.
Measuring the rate of expansion helped scientists determine the age of the universe.
The Universe is approximately 13.7 billion years old
Cosmic background radiation is evidence left over from Big Bang
Scientists believe that if we could rewind the Universe like rewinding a film, it would put all the matter back into a single place.