Faint Young Sun Paradox
Listen to part of a lecture in an astronomy class.
- What is the main propose of the lecture?
- A. To compare solutions to the greenhouse-gas problem.
- B. To examine methods used to study star formation in other solar systems.
- C. To discuss evidence for liquid water on young Earth and Mars.
- D. To discuss attempts to solve a puzzle related to the Sun.
- Why is geological evidence of liquid water on Earth and Mars three to four billion years ago problematic?
- A. It suggests that the solar system is younger than it could possibly be.
- B. It suggests that the young Sun was less bright than it is today.
- C. It challenges the prevailing model of star formation.
- D. It contradicts theories about the beginning of the universe.
- Why did the greenhouse-gas solution fail to explain the early presence of liquid water on Earth and Mars?
[CHOOSE 2 ANSWERS]
- A. The types of gases that were present in their atmospheres could not have caused temperatures to rise.
- B. There was insufficient carbon dioxide in their atmospheres to produce a greenhouse effect.
- C. Solar radiation would have destroyed the ammonia in their atmospheres.
- D. Clouds of ammonia would have lowered temperatures by blocking out sunlight.
- Why does the professor mention the solar wind?
- A. To explain a way the Sun is losing mass.
- B. To point out that it was less intense billions of years ago.
- C. To suggest a reason for early climate differences between Earth and Mars.
- D. To explain the importance of solving the faint-young-Sun paradox.
- What factor did astronomers consider when calculating the required solar mass for liquid water to exist on Earth and Mars?
- A. The young Sun lost mass at a slower rate than it currently does.
- B. The young Sun was closer to the planets than it currently is.
- C. The young Sun had less solar wind activity than it currently does.
- D. The young Sun comprised greater amounts of helium than it currently does.
- What is the professor’s attitude about the bright-young-Sun solution?
- A. He is surprised that it is not more widely accepted.
- B. He feels that it raises too many unanswerable questions.
- C. He is confident that future research will determine whether it is true.
- D. He expects that other possible solutions to the paradox will be proposed.
D C BC A B C