Question

question 11 if the nearest star is 4.2 light - years away, then the star is 4.2 million au away. the star must be very old. the star must be very young. the light we see left the star 4.2 years ago.

Explanation:

A light - year is the distance light travels in a year. So light from a star 4.2 light - years away took 4.2 years to reach us.

Answer:

the light we see left the star 4.2 years ago.