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
Motion of Stars at the Poles
Average Global Temperature Rise over the Past Century
A Global Bloom: Cities With Over One Million Residents
Areas of the United States, Mexico, and Cuba will be affected by a rise of just 100 cm
The Nile Delta will be strongly affected by a rise in sea level of 50 cm
Earth 600 Million Years Ago