Question

which of the following is not an explanation for changing brightness of a star?
objects obstructing the light reaching earth
changes in mass
parallax
changes in luminosity

Explanation:

• Objects obstructing the light reaching Earth: Can cause a star's brightness to change (e.g., in eclipsing binary systems).
• Changes in mass: Can affect a star's luminosity (related to brightness).
• Parallax: Parallax is a method used to measure the distance to a star. It is not related to the actual change in a star's brightness.
• Changes in luminosity: Directly related to a star's brightness.

Answer:

Parallax