The total power of radiation emitted by a star is called:

Correct Answer: Luminosity

Luminosity is the total amount of energy emitted by a star in the form of electromagnetic radiation per second. Unlike apparent brightness, which depends on the distance between the star and the observer, luminosity is an intrinsic property of the star itself. It is determined mainly by the star's size and surface temperature, following the Stefan-Boltzmann Law. Astronomers use luminosity to classify stars, estimate their ages, and understand their stages of evolution. The Sun's luminosity serves as a standard unit for comparing the brightness of other stars throughout the universe.

• Definition: Total energy emitted per second.
• Independent Of: Distance from Earth.
• Depends On: Star's size and temperature.
• Used In: Stellar classification and astronomy.
• Correct Answer: Luminosity.