If a star is moved twice as far away, its brightness would be reduced to one-fourth of its original brightness.

Here's why:

* Inverse Square Law: The brightness of a star (or any light source) decreases with the square of the distance. This is known as the inverse square law.

* Double the Distance: If you double the distance, the light has to spread out over an area four times larger.

* Reduced Brightness: Since the same amount of light is spread over a larger area, the brightness at any specific point is reduced to one-fourth.