What term describes the brightness of a star in comparison to the sun?

The term that describes the brightness of a star in comparison to the sun is "luminosity." Luminosity refers to the total amount of energy emitted by a star per unit time, typically measured in watts. When comparing stars, luminosity allows us to understand how much brighter or dimmer a star is relative to the sun. It takes into account not only the apparent brightness but also the distance from the observer, providing a standardized measure for comparison.

Other terms such as magnitude refer specifically to the brightness of objects as perceived from Earth, which can vary based on distance and other factors; illumination typically relates to the intensity of light that reaches a surface; radial brightness is not commonly used in astronomical contexts and does not accurately convey the concept of comparing a star's brightness to that of the sun. These terms, while related to light and brightness, do not capture the essence of comparing a star's overall energy output to that of our sun in the same way that luminosity does.