Author Question: The fact that the life on Earth seems to have appeared quite rapidly suggests that life A) can ... (Read 50 times)

tingc95 · **on:** Jul 27, 2018

The fact that the life on Earth seems to have appeared quite rapidly suggests that life

A) can arise on most habitable worlds
B) can only appear soon after a planet forms
C) on any kind of planet is inevitable
D) is only possible on Earth-like planets

Question 2

Suppose we observe a source of X-rays that varies substantially in brightness over a period of a few days. What can we conclude?

A) The X-ray source is a quasar.
B) The X-ray source contains a black hole with an accretion disk.
C) The X-ray source is no more than a few light-days in diameter.
D) The X-ray source must have a strong, rapidly varying magnetic field.
E) We are seeing the rapid orbit of two stars in a binary system.