AST201H1 Lecture 8: Lecture 8 Notes

Suppose you have a light bulb that emits 200 watts of visiblelight.How far away would you have to put the light bulb forit to have thesame apparent brightness as Alpha Centauri A in oursky? (Hint: Use200 watts as L in the inverse square law for light,and use theapparent brightness given above for Alpha Centauri A.Then solve forthe distance.)

The apparent brightness of a star depends only on its luminosity.

as the distance of a star doubles, what happens to its apparent brightness?

Pluto's apparent magnitude is approximately 14. According to Figure10.6 in the textbook (Apparent Magnitude), Pluto can be seen?