Chapter 17, Problem 1E

What two factors determine how bright a star appears to be in the sky?

To determine

Two factors that determines the brightness of the star.

Explanation of Solution

Introduction:

Luminosity and distance are the two factors that determines the brightness of the star.

Luminosity

Luminosity is the total radiative power radiated by stars into space. It is total amount of electromagnetic power emitted by galaxy, star or astronomical object. It gives direct indication of brightness of the stars. It is a logarithmic measure of brightness of the stars. Distance

Brightness of the stars depends upon the amount of starlight reaching to the earth. More the distance lesser will be the amount of starlight and hence lesser will be the brightness of the stars. So, the distance is also important factor to measure the brightness of the stars.

Conclusion:

Luminosity and distance are the two factors that determines the brightness of the star.