Astronomy Cosmology and Deep Space 2 — Questions and Answers
Question 1: What observation provided the first strong evidence that the universe is expanding?
- The redshift of distant galaxies increasing with distance (Correct answer)
- The blueshift of nearby stars
- The constant brightness of Cepheid variables
- The uniform color of the night sky
Correct answer: The redshift of distant galaxies increasing with distance
Edwin Hubble found that more distant galaxies show greater redshift, indicating the universe is expanding.
Question 2: The Cosmic Microwave Background radiation is best described as what?
- Leftover heat from the early hot universe (Correct answer)
- Light emitted by the Milky Way's core
- Radiation from a nearby quasar
- Reflected sunlight from cosmic dust
Correct answer: Leftover heat from the early hot universe
The CMB is relic radiation released about 380,000 years after the Big Bang when atoms first formed.
Question 3: Approximately what percentage of the universe's total energy content is dark energy?
- About 68% (Correct answer)
- About 27%
- About 5%
- About 90%
Correct answer: About 68%
Dark energy makes up roughly 68% of the universe, driving its accelerating expansion.
Question 4: What is the approximate age of the universe according to current measurements?
- 13.8 billion years (Correct answer)
- 4.6 billion years
- 100 billion years
- 6,000 years
Correct answer: 13.8 billion years
The universe is about 13.8 billion years old based on CMB and expansion data.
Question 5: A galaxy far away shows its spectral lines shifted toward longer wavelengths. This indicates it is:
- Moving away from us (Correct answer)
- Moving toward us
- Stationary relative to us
- Cooling rapidly
Correct answer: Moving away from us
A shift to longer (redder) wavelengths is a redshift, meaning the galaxy is receding.
Question 6: Which term describes a region of space where gravity is so strong that nothing, not even light, can escape?
- Black hole (Correct answer)
- Nebula
- Pulsar
- White dwarf
Correct answer: Black hole
A black hole has gravity strong enough to trap light beyond its event horizon.
Question 7: The Big Bang theory predicts that in the early universe, matter was:
- Extremely hot and dense (Correct answer)
- Cold and diffuse
- Made only of iron
- Frozen and solid
Correct answer: Extremely hot and dense
The early universe was in an extremely hot, dense state that expanded and cooled over time.
Astronomy Cosmology and Deep Space 2
What observation provided the first strong evidence that the universe is expanding?