Final answer:
Brightness in the context of pixels and images refers to the intensity of light. In astronomy, apparent brightness signifies the amount of light from an object that is received on Earth and is influenced by the object's luminosity and distance from Earth.
Step-by-step explanation:
The question 'brightness is defined as the ___ of light of the various pixels that make up the image' refers to the intensity of light. In astronomy, this concept is termed as apparent brightness, which is a measure of the amount of light received by Earth from a celestial object, indicating how bright an object appears in our sky. This measure takes into account the total energy output of a star, known as its luminosity, as well as its distance from Earth. The apparent brightness is what we observe when we look at the stars in the night sky, with some stars appearing brighter than others due to their luminosity and proximity to Earth. For example, a star that is closer to Earth will generally appear brighter than a star that is farther away, even if both stars have the same luminosity. Apparent brightness is often expressed in magnitudes, highlighting how human vision perceives light intensity.