Question

scientists are observing three stars in space and look at the brightness of the three stars. if they were all the same distance from earth to determine their actual brightness. using this information, scientists are determining the select of the stars. scientists study one of these stars and realize that as the star gets closer, it gets brighter. they are observing the select of the star.

Explanation:

For the first blank: When scientists determine the actual brightness of stars at the same distance from Earth, they are finding the luminosity (intrinsic brightness) of the stars. Luminosity is the total amount of energy a star emits per unit time, and by controlling for distance (since they are same distance), they can assess this intrinsic property.

For the second blank: When they observe how bright a star appears as its distance changes (here, as it gets closer, it appears brighter), they are observing the apparent magnitude (or apparent brightness) of the star. Apparent brightness depends on both the star’s luminosity and its distance from the observer (Earth, in this case).

Answer:

First blank: Luminosity
Second blank: Apparent brightness (or Apparent magnitude)

(Note: If the options for the dropdowns include "luminosity" for the first and "apparent brightness" / "apparent magnitude" for the second, those would be the correct selections. The exact terminology may align with standard astronomy terms where luminosity is intrinsic brightness at a standard distance, and apparent brightness is how bright it looks from Earth, dependent on distance.)