Comparing this to their apparent brightness, one can determine their distance.

A variable star is a star whose apparent brightness changes over time.

(a)The distance to a light cannot be reliably estimated from its apparent brightness.

In a way, this sort of validates me as a human and my apparently formerly secret brilliance.

By comparing their intrinsic brightness with their apparent brightness as seen from Earth, scientists can calculate their distances.

By analyzing these gravitational lens distortions, nearby mass concentrations can be found, regardless of how bright they appear.

By comparing their intrinsic brightness as measured by Hubble, with their apparent brightness as seen from Earth, scientists can calculate their distances.

By comparing their intrinsic brightness — measured with Hubble — with their apparent brightness as seen from Earth, scientists can calculate their distances.

This invigorating charcoal face mask draws out impurities and refines the appearance of pores for healthy-looking skin with a glow that shows.

If we know the distance of a star and measure how bright it looks in the sky, we can calculate its luminosity.

R Coronae Borealis stars can see their apparent brightness unpredictably decline to a thousandth of their nominal value within a few weeks, with the return to normal light levels being much slower.