If we imagine that 1 in 10 million stars would eventually give rise to a civilization on an orbiting planet and assuming that there are 100 billion stars in our Milky Way galaxy, how often should a civilization randomly appear over a 5 billion year
period? A) once every 50 million years
B) once every 50,000 years
C) once every 500,000 years
D) once every 5 million years
Question 2
Rayleigh scattering would have 400. nm light be scattered how many times as much as 800. nm light?
A) 32
B) 4
C) 8
D) 2
E) 16
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