Self-study
P1
A vigorous debate in astronomy centers on an epoch in planetary history that was first identified by analysis of rock samples obtained in lunar missions. ██████████ ██████████ ████ ███ █████ ███████ ██ ███ ████ ████ ███████ ██ █ ████████ ███████████ ██ ██████ █████████████ ████ ███████ █████ █████████ █████████ ████ █████ ███████████ ██████ ███████████ ████ ████ ███████████ ████ ████████ ███ ████
Phenomenon ·
Late heavy bombardment
4 billion years ago, Moon and Earth were both massively bombarded with projectiles.
P2
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Hypothesis 1 ·
Large asteroid or comet disintegration
Evidence: size of lunar craters is large, suggests a large asteroid or comet broke apart and bombarded inner solar system with debris.
Hypothesis 2 ·
"LHB" is just a part of an even longer period of bombardment
"LHB" is part of a continuous bombardment that lasted billions of years. "LHB" just happened to be last and hence obliterated evidence of earlier impacts.
Hypothesis 3 ·
LHB only affected Earth-Moon system
Contra hypothesis 1 which claims that LHB affected entire inner solar system (Mars, Earth, Venus, and Mercury).
P3
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Evidence Supporting Hypothesis 1 ·
Mars rock found on Earth
Mars rock dates to same time as LHB, suggesting that Mars experienced bombardment too
Conclusion ·
LHB wasn't just an Earth-Moon phenomenon
At least Mars experienced it too.
Further Research ·
To decide between the different hypotheses
Passage Style
Critique or debate
Phenomenon-hypothesis (RC)
11.
The author implies that all ███████████ ██████████ ██ ███ ███ █████ █████ ██ █████ ███ ██ ███ ██████████
a
the approximate duration ██ ███ ███
The three hypotheses do not agree about the approximate duration of the LHB. Hypothesis 1 is silent on the topic of duration, Hypothesis 2 claims that the LHB would have
b
the origin of ███ ██████ ████████ ██ ███ ███
Hypothesis 1
c
the idea that █████████ █████████ █████████████ █████ ███ ███
All three hypotheses agree that the LHB eventually ended. The LHB is what caused the
d
the idea that ███ ███ █████████ ███ ████ ████ ███████ ██ █████ ████ ███████ █████ ███
We know that life could not have survived until after the LHB. The passage is silent on what happened with regards to life before the LHB. Thus, the passage does not suggest that the author believes that all three hypotheses agree with (D), because we just don’t know what the hypotheses say about this claim.
e
the approximate amount ██ ██████ ████████ ██ ███ ███
We can’t say that the author implies that all three hypotheses agree with this claim. The hypotheses don’t specifically talk about the amount of debris involved. We do know that Hypothesis 3 says that the debris from the LHB would have been swept up