Ch. 4 Sec. 5 The Expanding Universe Discover activity- How Does the Universe Expand pg. 148 1.What...
Transcript of Ch. 4 Sec. 5 The Expanding Universe Discover activity- How Does the Universe Expand pg. 148 1.What...
Discover activity-How Does the Universe Expand pg. 148
1. What happens to the distances between galaxies that are close together?
2. What happens to the distances between galaxies that are far apart?
3. If the universe is expanding, do galaxies that are close together move apart faster or slower than galaxies that are far apart? Explain.
Big Bang Theory• theory that universe formed in an instant, billions of yrs. ago, in an enormous explosion
Edwin Hubble• discovered :
1.galaxies are moving away from us & each other
2. relationship between distance to a galaxy & its speed
The galaxies in the universe are like the raisins in rising bread dough.
How does rising raisin bread dough resemble the expanding universe?
cosmic background radiation
• faint radiation glow that comes from all directions in space
• leftover thermal radiation from the big bang
2. Gravity pulled solar
nebula together
4. Solar nebula flattened- formed a rotating disk
dark matter
•cannot be seen directly-presence can be inferred by effects of its gravity on visible objects
What was the big bang?
• Giant explosion after which all of the matter in the universe began moving apart
Describe two pieces of evidence that support the
big bang theory?
1. Hubble’s law- the observation that the farther away a galaxy is, the faster it is moving away from Earth
2. cosmic background radiation-radiation left over from the big bang
What force caused the solar system to form?
• Gravity pulled the solar nebula together and them pulled most of the gas into the center of the disk, where the gas eventually became hot and dense enough for nuclear fusion to begin and form the sun
Place the following events in the proper order:
• planets form
• planetesimals form
• solar nebula shrinks
• nuclear fusion begins in the sun
How do scientists know that dark matter exists?
• Its presence can be inferred by observing the effect of its gravity on visible objects, such as stars, or on light