Most of the moons of Saturn have rocky, cratered surfaces, like Deimos and Phobos.
Indicate whether the statement is true or false
Question 2
Why is it thought that quasars probably spend only a fairly short time in their highly luminous phase?
A) because there aren't many quasars around today
B) because there aren't any quasars closer than about a redshift of 1
C) because all quasars are at about the same epoch, narrowly defined in time
D) because a black hole could not power a highly luminous quasar for more than a few million years
E) because quasars are known to be the consumers of massive galaxies