Relative brightness and Absolute brightness

 Relative brightness and Absolute brightness

When one star is 8 light years away, another star is 100 light years away. But to our eyes, both stars appear to be in the same plane.

 And the star that is 8 light years away may appear to be the brighter of the two stars. But the star that is 100 light years away may be much brighter.

 For these reasons, scientists wanted to measure the absolute brightness of stars.

Scientists use a mathematical method for this. That is, any star we can see is placed 10 light-years away and its brightness is measured.

 That is, a star located 100 light-years away is measured when it is 10 light-years away, and a star located 8 light-years away is measured when it is 10 light-years away.

 Then, the brightness of these two stars can be compared and we can understand which star is brighter. When our Sun is 10 light-years away, its brightness is +4.85. At its current location, the Sun's brightness is -26.7. 

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