The Universe
The universe is composed of matter and energy. All of the matter in the universe now was in the universe when it formed. There is evidence to support that scientists are able to estimate the age of the universe in two ways.
First Way to Determine Age is by looking for the oldest stars.
Nebula (gas and dust) exist in space and are remnants from the formation of the universe. Stars undergo a life cycle based on the composition of the gases within them. As stars age the amount of hydrogen in the star changes, therefore changing the color and brightness of the star.
Look at the H-R Diagram on page 388 in textbook. Next, look at the life cycle of a star on page 391.
After studying the two images which stars are the oldest on the H-R Diagram? ______and the ______. How did you determine this? ______
______
Second Way to Determine Age is by measuring the rate of expansion of the universe.
Astronomers determined the galaxy is expanding based on the color of light emitted from galaxies and stars. As the universe expands and galaxies move apart, the wave-length of light emitted from those galaxies is stretched. This shifts the light toward the red end of the spectrum and is called “red-shift”. The more distance or faint a galaxy the more rapidly it is moving away from Earth.
Look Figure 20 on page 397. You’re looking at the visible light spectrum given off by a star moving by the Earth. If the dark abortion lines are near the red end of the spectrum, what does that mean?
______
If the dark abortion lines are near the blue end of the spectrum, what does that mean? ______
______
The universe began with a period of extreme and rapid expansion
Once scientists determined that the universe was expanding, they developed many theories to explain their observations. The leading theory about the formation of the universe is the Big Bang Theory.
Look on page 399 and answer the following.
How did the universe begin? ______
How old is the universe? ______
???? Which is older, the universe or Earth? ______Why? ______