An astronomer states that Star P has a lower absolute brightness than Star Q. How would you translate this observation for a non scientist?

Star P is smaller than star Q

Explanation:

Absolute brightness is defined as brightness of a celestial object or star from a Standard distance usually taken as 10 parsecs from Earth. If one star is brighther than the other then there can be two variable playing major role given that they are at same distance -

a) composition of star and

b) Its size.

The larger the star, the more energy it will emit per second and hence more will be its absolute brightness.

Thus, star P is smaller than star Q